Skip to main content

21st Century and Contemporary Link Necklaces

to
299
1,948
1,041
795
777
650
1,354
249
145
99
87
10
117
1,539
25
12
27
22
39
88
113
137
286
158
5
1,353
869
26
777
161
125
98
61
to
80
64
41
34
29
645
483
70
60
18
11
7
6
6
4
4
3
3
1
1
2,141
107
1,719
350
Period: 21st Century and Contemporary
Cushion Cut Rubellite Tourmaline Diamond Curb Chain Necklace 18K Yellow Gold
Located in Scottsdale, AZ
This striking necklace features a richly saturated 181.65 carat deep pink rubellite tourmaline set at the center, glowing with intense color and depth. A shimmering diamond halo fram...
Category

Contemporary 21st Century and Contemporary Link Necklaces

Materials

Diamond, Rubelite, Tourmaline, Gold, 18k Gold, Yellow Gold

14.25 Carat SI/H Natural Diamond Yellow Gemstone Necklace 14 Karat White Gold
Located in Diera, Dubai
This 14.25 Carat SI/H Natural Diamond Yellow Gemstone 14 Karat White Gold Necklace features heart-shaped yellow gemstone at the center, framed by a chain of brilliant cut white diamo...
Category

American Modern 21st Century and Contemporary Link Necklaces

Materials

Diamond, Gold, White Gold, 14k Gold

Sunita Nahata Zambia Emerald 5.83ct. Necklace in 18KWG with White Diamond.
Located in Hong Kong, HK
A statement of unparalleled luxury, this breathtaking necklace showcases a pear-shaped Zambian emerald. The necklace itself is a masterpiece of craftsmanship, designed with a graduat...
Category

Thai Contemporary 21st Century and Contemporary Link Necklaces

Materials

Diamond, White Diamond, Emerald, 18k Gold, White Gold

Van Cleef Arpels Pure Alhambra Fourteen Motifs Diamond Yellow Gold Necklace
Located in Southampton, PA
18k Yellow Gold Pure Alhambra 14 Motifs Diamond Necklace by Van Cleef & Arpels. With 14 diamond pave Alhambra motifs 16mm each VVS1 clarity, E color total weight approximately 5.45ct...
Category

French 21st Century and Contemporary Link Necklaces

Materials

Diamond, Yellow Gold

Vivid Diamonds 12.45 Carat Diamond Necklace
Located in Miami, FL
Stunning Vivid Diamonds diamond necklace crafted in yellow gold, featuring 541 round brilliant cut diamonds weigh 12.45 carats total, G-H color, SI clar...
Category

American Modern 21st Century and Contemporary Link Necklaces

Materials

Diamond, 14k Gold, Yellow Gold

PANIM 20 Carat Pave Set Diamond 18k White Gold Cuban Necklace
Located in Tsim Sha Tsui, Hong Kong
PANIM 20 Carat Pave set Diamond 18K White Gold Cuban Necklace Wearing a diamond Cuban chain is a great way to elevate your style and make a statem...
Category

Indian Modern 21st Century and Contemporary Link Necklaces

Materials

Diamond, White Diamond, 18k Gold, White Gold

JR 2.13 Carat White Rose Cut 18 Karat White Gold Necklace
Located in Hong Kong, HK
JR 2.13 Carat White Rose Cut 18 Karat White Gold Necklace The necklace is made with 15pcs of White Rose cut Drilled Diamond . It has small gold ring near the clasp to adjust the len...
Category

Hong Kong Modern 21st Century and Contemporary Link Necklaces

Materials

Diamond, 18k Gold, White Gold

Nicolis Cola 18k Yellow Gold 19" Hammered Florentine Oval Rolo Link Necklace
Located in Montclair, NJ
Heavy Substantial Statement Necklace!! Material: Solid 18k Yellow Gold Weight: 166.88 Grams Chain Type: Open Oval Rolo - Unique! Chain Length: 19 inches (measured next to ruler) (W...
Category

21st Century and Contemporary Link Necklaces

Materials

Gold, 18k Gold, Yellow Gold

14 Karat Yellow Gold Hammered Link Necklace 31.24 Grams 20 Inches
Located in New York, NY
14 Karat Yellow gold hammered link necklace weighing 31.24 grams, 20 inches long. Match bracelet. Necklace can be made longer. DM for pricing.
Category

Contemporary 21st Century and Contemporary Link Necklaces

Materials

14k Gold, Yellow Gold

Christian Dior necklace
Located in SAINT-OUEN-SUR-SEINE, FR
DIOR - Silvery metal short necklace composed of several tiny chains and pearly-effect resin. A Collection circa 2000, under the artistic direction of John Galliano Condition: Very g...
Category

French 21st Century and Contemporary Link Necklaces

Braccio Solid 14k Yellow Gold Men s Chain 46 Grams Necklace
Located in Vernon Hills, IL
This stunning men's chain necklace is made of solid 14k yellow gold. The necklace weighs 46 grams and measures 22". The piece features a durable lobster clasp. B-3121
Category

North American Art Deco 21st Century and Contemporary Link Necklaces

Materials

14k Gold, Yellow Gold

36.7 Carat Zambian Emerald 17.63 Carat SI/H Diamond Necklace 18 Karat White Gold
Located in Diera, Dubai
Details Item Code :- SEN-51615 Gross Wt. :- 74.09 gm 18k White Gold Wt. :- 63.22 gm Natural Diamond Wt. :- 17.63 Ct. ( AVERAGE DIAMOND CLARITY SI1-SI2 & COLOR H-I ) Zambian Emerald ...
Category

American Modern 21st Century and Contemporary Link Necklaces

Materials

Diamond, Emerald, 18k Gold, White Gold

GIA Certified 49.00 Carat Diamond Tennis Necklace
Located in New York, NY
The three center diamonds are certified. Features 49.00 Carats of Ideal Cut Diamond. The center stone is 3.83 Carats GIA Certified J color SI in Clarity, next two stones are 2.25 a...
Category

American 21st Century and Contemporary Link Necklaces

Materials

Diamond, Platinum

Men s Yellow Gold Diamond Cuban Link Necklace
Located in New York, NY
14KT yellow diamond Cuban link necklace 16.00ct total weight of pave diamonds, 24" This product comes with a certificate of appraisal This...
Category

American 21st Century and Contemporary Link Necklaces

Materials

Diamond, White Diamond, 14k Gold, Yellow Gold

JR 3.17 Carat Rose Cut Diamond Dangling Necklace 18 Karat White Gold
Located in Hong Kong, HK
JR 3.17 Carat Rose Cut Diamond Dangling Necklace 18 Karat White Gold This contemporary piece of necklace is made of Drilled Rose cut diamond and it eludes femininity & grace. Diamon...
Category

Hong Kong Modern 21st Century and Contemporary Link Necklaces

Materials

Diamond, 18k Gold, White Gold

Beauvince Graduated Riviera Space Tennis Diamond Necklace in Platinum
Located in New York, NY
A classic and elegant everyday or occasional wear with graduating diamond sizes, this Space Necklace is a fresh take on a versatile piece of jewelry. All our necklaces have two locks...
Category

Contemporary 21st Century and Contemporary Link Necklaces

Materials

Diamond, White Diamond, Platinum

Open Link 22k Yellow Gold Necklace by Gurhan
Located in Beverly Hills, CA
A masterpiece of artisanal craftsmanship, this striking 22K yellow gold open-link necklace, attributed to Gurhan, embodies effortless sophistication. Featuring a textured and hammere...
Category

21st Century and Contemporary Link Necklaces

Materials

Yellow Gold, 22k Gold

Italian Solid 10k Gold Diamond 17" Wide Flat Byzantine Link Chain Necklace
Located in Montclair, NJ
--Stone(s):-- (14) Natural Genuine Diamonds - Single Cut - Pave Set - White Diamonds - Accents on Clasp Area Material: Solid 10k Yellow Gold w/ White Gold Accents Weight: 28.87 Gram...
Category

Italian 21st Century and Contemporary Link Necklaces

Materials

Diamond, Gold, 10k Gold, White Gold, Yellow Gold

Classic Men s Solid 10k Yellow Gold 24" Curb Cuban Link Chain Necklace
Located in Montclair, NJ
Material: Solid 10k Yellow Gold - Semi Hollow Design Weight: 53.10 Grams Chain Type: Curb/ Cuban Link Chain Length: 24 inches (measured next to ruler) Chain Width: 9.4mm (0.37")(appr...
Category

21st Century and Contemporary Link Necklaces

Materials

Gold, 10k Gold, Yellow Gold

Braccio Solid 14k Yellow and White Gold Men s Chain 182 Grams Necklace
Located in Vernon Hills, IL
This stunning men's chain necklace is made of solid 14k yellow/white gold. The necklace weighs 182 grams and measures 23". The piece features a durable lobster clasp. B-3121
Category

North American Art Deco 21st Century and Contemporary Link Necklaces

Materials

14k Gold, Yellow Gold, White Gold

GIA Certified 95.98 Carat Fancy Sapphire and White Diamond White Gold Necklace
Located in New York, NY
36 Fancy Sapphire Gemstones: 92.89 Carats 210 White Diamonds: 3.09 Carats Metal: 18K White Gold, 32.80 Grams GIA Certificate # 2235376350
Category

21st Century and Contemporary Link Necklaces

Materials

White Diamond, Sapphire, 18k Gold, White Gold

Vintage 2000 14 Karat Yellow Gold Italian Wide Link Necklace
Located in Boston, MA
Vintage 1990's 14K Yellow Gold Italian Wide Link Necklace - The Italian made link necklace is 11mm wide and 16.75 inches long. It features a hidden ...
Category

Italian Modern 21st Century and Contemporary Link Necklaces

Materials

14k Gold, Yellow Gold

107 Carat Diamond Necklace
Located in New York, NY
Magnificent 18K white gold diamond necklace, features round brilliant cut diamonds, all collection quality diamonds, connected by 19 circles, totaling 107 carats (also has matching ...
Category

American 21st Century and Contemporary Link Necklaces

Materials

Diamond, White Diamond, 18k Gold, White Gold

Diamond Wreath Necklace
Located in New York, NY
An elegant and timeless design. 30.95 carats of white pear, marquise and round brilliant cut diamonds set in platinum. 16 inch length.
Category

21st Century and Contemporary Link Necklaces

Materials

Diamond, Platinum

David Webb Rubelilte Turquoise Diamond Necklace Earrings Set
Located in New York, NY
David Webb Rubellite Turquoise Diamond Necklace Earrings Set. A necklace featuring step-cut and oval rubellite, cabochon turquoise, brilliant-cut diamonds weighing appro...
Category

American 21st Century and Contemporary Link Necklaces

Materials

Diamond, Rubelite, Turquoise, 18k Gold, Yellow Gold, Platinum

12.34 Carat Total Round Diamond Woven Braid Collar Necklace 14 Karat White Gold
Located in Scottsdale, AZ
This luxurious, graduated diamond necklace will be your go-to piece for all your special occasions. Its timeless style and feminine design will elevate any look that it's paired with...
Category

Unknown Contemporary 21st Century and Contemporary Link Necklaces

Materials

Diamond, Gold, White Gold, 14k Gold

Multicolor Sapphires, Topazs, Diamonds, 14 Kt Rose Gold and White Gold Necklace
Located in Marcianise, Marcianise (CE)
Elegant tennis necklace in 14 kt rose gold structure mounted with multicolor sapphires, topazs,peridots,garnets and iolite for all the lenght.In the final part, laterally, leaves in ...
Category

Italian Retro 21st Century and Contemporary Link Necklaces

Materials

Diamond, Sapphire, Topaz, 14k Gold, Rose Gold, White Gold

18 Karat Yellow Gold Groumette Wood and Amber Necklace
Located in Milano, IT
In this exquisite necklace, oval rings of different shapes alternate to create a modern design that is striking and sophisticated. Among the several wooden rings, there are two made ...
Category

Italian 21st Century and Contemporary Link Necklaces

Materials

18k Gold, Yellow Gold

Vintage 14K Solid Yellow Gold Curb Link Chain, 25.7 Gm , 23" Long Made in Turkey
Located in New York, NY
Vintage 14K Solid Yellow Gold Curb Link Chain , 25.7 Gm , 23 " Long Lobster Lock For those in search of high-quality, authentic gold jewelry, this Vintage 14 Kt Yellow Gold link chai...
Category

21st Century and Contemporary Link Necklaces

Materials

14k Gold, Yellow Gold

Natural Round Brilliant Cut Certified Diamond Chain Necklace in 18K White Gold
Located in New York, NY
Fine Jewelry Natural Round Brilliant Cut Certified Diamond Chain Necklace in 18K White Gold. This stunning piece of jewelry instantly elevates a casual look or dressy outfit. April ...
Category

American Modern 21st Century and Contemporary Link Necklaces

Materials

Diamond, Gold, 18k Gold, White Gold

6.62 Carat Round Diamond 18" Tennis Necklace 14 Karat In Stock
Located in Boca Raton, FL
Material: 14k Rose Gold Diamond Details: Approx. 6.62ctw of round cut Diamonds. Diamonds are G/H in color and VS in clarity Clasps: Tongue in box with safety clasp Total Weight: 16.7...
Category

American 21st Century and Contemporary Link Necklaces

Materials

Diamond, White Diamond, 14k Gold, Rose Gold

14 Karat Yellow Gold Satin Polish Link Necklace 34.2 Grams Italian
Located in New York, NY
14 Karat Yellow Gold link necklace featuring alternate oval satin & polish links weighing 34.2 grams, 30.5 inches. Ovals measure 0.63 *0.45 inches Made in Italy
Category

Contemporary 21st Century and Contemporary Link Necklaces

Materials

14k Gold, Yellow Gold

14 Karat Rose Gold Diamonds by the Yard Necklace
Located in Los Angeles, CA
Specifications: diamonds: 8 PIECES ROUND DIAMOND carat total weight: APPROX .10 CTw color: G clarity: VS metal: GOLD type: Diamonds by the Yard weight:...
Category

American Contemporary 21st Century and Contemporary Link Necklaces

Materials

Diamond, 14k Gold, Rose Gold

GIA Certified 3ct Round-Cut Natural Diamond Tennis Necklace – 18K White Gold
Located in Jaipur, RJ
💎 Product Description: An eternal symbol of sophistication, this Diamond Tennis Necklace embodies pure elegance and brilliance. Showcasing a magnificent 3.01ct natural round-cut dia...
Category

Indian Art Deco 21st Century and Contemporary Link Necklaces

Materials

Diamond, Gold, 18k Gold, White Gold

64.14ct Rainbow Tourmaline Diamond Halo Statement Necklace in 18K White Gold
Located in Great Neck, NY
An extraordinary blend of color, craftsmanship, and elegance, this luxury tourmaline and diamond necklace is a rare statement of artistry and refinement. Featuring a remarkable 64.14...
Category

Modern 21st Century and Contemporary Link Necklaces

Materials

Diamond, White Diamond, Tourmaline, Gold, 18k Gold, White Gold

Contemporary Natural Pearl Necklace with Titanium Rods GIA-Certified
Located in Miami Beach, FL
A contemporary reinterpretation of the classic pearl necklace, this sculptural design brings together traditional materials and modern construction. The necklace features a total of ...
Category

Contemporary 21st Century and Contemporary Link Necklaces

Materials

Natural Pearl, Titanium

Vintage Sterling Faceted Black Onyx Necklace 18 Inches
Located in Webster, SD
This gorgeous vintage necklace is sterling silver. It features 15 faceted 7x9mm onyx stones. This necklace is adjustable from 18 to 20 inches. Marks: Sam, 925, India Weight: 17 gra...
Category

Indian Contemporary 21st Century and Contemporary Link Necklaces

Materials

Onyx, Sterling Silver

13.03 Carat Diamond Pave Cuban Chain Necklace 14 Karat in Stock
Located in Boca Raton, FL
Style: 14k Two Tone 13.03ctw Diamond Pave Cuban Chain Necklace Material: 14k white gold & 14k rose gold Stone Details: Approx. 13.03c...
Category

American 21st Century and Contemporary Link Necklaces

Materials

Diamond, White Diamond, 14k Gold, Rose Gold, White Gold

Ruby with Diamond Necklace set in 18K Gold Settings
Located in Bangkok, TH
Ruby 46.20 carats with Diamond 4.55 carats Necklace set in 18K Gold Settings Width: 1.2 cm Length: 40.0 cm Total Weight: 54.75 grams "We first opened doors in 1980 when it was the...
Category

Thai Contemporary 21st Century and Contemporary Link Necklaces

Materials

Diamond, Ruby, 18k Gold

Tiffany Co. Keys Petals Diamond Platinum Key Pendant Necklace
Located in Banbury, GB
SKU 33301831 Comes With Box Only RRP £12,000 Incl. Taxes / €14,900 Incl. Taxes / $14,900 Excl. Taxes Model Keys Metal Platinum Stones Diamond Weight Approximately 12.38 g Length Appr...
Category

American 21st Century and Contemporary Link Necklaces

Materials

Diamond, Platinum

Tiffany Co Atlas Diamond Yellow Gold Necklace
Located in New York, NY
Tiffany & Co 18k yellow gold Atlas necklace, featuring ten diamond links - approximately 1.00ctw G/VS. Necklace is 16.5" long and 1/8" wide. Hallmarked Tiffany & Co, 1995, 750. Weig...
Category

American 21st Century and Contemporary Link Necklaces

Materials

Diamond, Yellow Gold

12.59 Carat Rainbow Multi Sapphire Baguette Tennis Necklace in 14k Yellow Gold
Located in New York, NY
Elevate your jewelry collection with this 12.59 Carat Rainbow Multi Sapphire Baguette Tennis Necklace in 14k Yellow Gold. Featuring a captivating array of 12.59 carats of meticulousl...
Category

American Modernist 21st Century and Contemporary Link Necklaces

Materials

Sapphire, Gold, 14k Gold, Yellow Gold

PANIM 10.95cts Rosecut Diamond Necklace in 18 Karat White Gold
Located in Tsim Sha Tsui, Hong Kong
PANIM 10.95cts Rosecut Diamond Necklace in 18 Karat White Gold In this necklace rosecut diamonds are evenly spaced on a white gold chain. Thi...
Category

Indian Edwardian 21st Century and Contemporary Link Necklaces

Materials

Diamond, White Diamond, 18k Gold, White Gold

20 Carat Diamond 14K White Gold Tennis Necklace – 17.5 Inches
Located in Chicago, IL
14K White Gold 20 Carat Diamond Tennis Necklace – 17.5 Inches Elegant and timeless, this dazzling tennis necklace features 109 round ...
Category

American Contemporary 21st Century and Contemporary Link Necklaces

Materials

Diamond, White Diamond, White Gold

16"-18" Natural White Diamond(4.56 carat) Necklace in 14 Karat White Gold
Located in New York, NY
A refined essential with effortless sparkle. This delicate 14 karat white gold necklace features faceted white diamond beads linked together and spaced gracefully along the chain, cr...
Category

American 21st Century and Contemporary Link Necklaces

Materials

White Diamond, White Gold, 14k Gold

Louis Fiessler 18k Rose Gold Link Necklace
Located in Cincinnati, OH
By designer Louis Fiessler, this heavy, solid rose gold link necklace will be an awesome addition to anyone's jewelry collection! 18 karat ros...
Category

Unknown 21st Century and Contemporary Link Necklaces

Materials

Diamond, 18k Gold, Rose Gold

10 Carat Round Diamond 16 Inches Tennis Necklace
Located in Chicago, IL
Exquisite 10 Carat Round Diamond Tennis Necklace Elevate your jewelry collection with this stunning 16-inch tennis necklace, crafted to showcas...
Category

Unknown Contemporary 21st Century and Contemporary Link Necklaces

Materials

Diamond, Gold, White Gold, 14k Gold

Pave White Diamond Cuban Link Necklace in 14K Yellow Gold
Located in Los Angeles, CA
Beautiful white diamond pave Cuban link necklace handmade in 14k yellow gold. Length is 16".
Category

21st Century and Contemporary Link Necklaces

Materials

White Diamond, Yellow Gold

Roman Malakov 18.38 Carats Total Oval Cut Ruby Diamond Tennis Necklace
Located in New York, NY
An incredible tennis necklace, showcasing 16.89 carats total of oval cut red rubies, each evenly spaced by two round brilliant cut diamonds weighing 1.49 carats total with F-G color ...
Category

American Contemporary 21st Century and Contemporary Link Necklaces

Materials

Diamond, Ruby, 14k Gold, White Gold

NWT $47, 500 Important 18KT Gold Large Fancy Emerald Diamond Strand Necklace
Located in New York, NY
The Following Item we are offering is a Rare Important Radiant 18KT Gold Necklace with Magnificent Large Fancy Oval Cut Emeralds Flanked by Fine Glittering White Diamonds Throughout....
Category

Unknown 21st Century and Contemporary Link Necklaces

Materials

Diamond, Emerald, Gold, 18k Gold

Natural Blue Topaz and Cubic Zirconia Station Wedding Necklace in 925 Silver
Located in New York, NY
This Natural Blue Topaz and Cubic Zirconia Station Wedding Necklace 925 sterling silver station necklace is adorned with luminous oval-cut blue topaz gemstones, beautifully accented ...
Category

American Modernist 21st Century and Contemporary Link Necklaces

Materials

Topaz, Zircon, Blue Topaz, Silver, Sterling Silver

Christian Dior Rose De Vents Mother Of Pearl Diamond Long Yellow Gold Necklace
Located in Southampton, PA
18k Yellow Gold Diamond Mother Of Pearl Dior Rose De Vents Long Necklace by Christian Dior. With 9x Mother of Pearl Stones - 11.5mm 9x Round Brilli...
Category

French 21st Century and Contemporary Link Necklaces

Materials

Diamond, Pearl, Yellow Gold

Bijoux Num Stunning Diamond Shape Cubic Zirconia Flexible Necklace
Located in Los Angeles, CA
Elegant diamond shape cubic zirconia necklace featuring over 500 pieces of round Cubic Zirconia individually handset in 18k gold & platinum rhodium p...
Category

Contemporary 21st Century and Contemporary Link Necklaces

Materials

Rhodium, Sterling Silver, Gold Plate, Vermeil

Silvorra Designer Modern Silver Unisex Necklace Jewelry for Thanksgiving gift
Located in New York, NY
A striking link chain necklace crafted from pure 925 sterling silver, designed with an intricate interwoven pattern that emphasizes strength and style. Weighing 58.4 grams, it offers...
Category

American Modernist 21st Century and Contemporary Link Necklaces

Materials

Silver, Sterling Silver

Louis Vuitton, Color Blossom Malachite and Diamond Station Long Necklace
Located in Chicago, IL
The Color Blossom pieces celebrate the emblematic Monogram Flower, designed in 1896 by Georges-Louis Vuitton, son of the founder. Set into 18-karat pink gold, this precious long neck...
Category

French Contemporary 21st Century and Contemporary Link Necklaces

Materials

Diamond, Malachite, 18k Gold, Yellow Gold

Italian Men s 10k Yellow Gold 21.5" Figaro Link Chain Necklace w/ Lobster Claw
Located in Montclair, NJ
Material: Solid 10k Yellow Gold - Hollow Design Weight: 12.3 Grams Chain Type: 21.5" - Figaro Link - Lobster Claw Clasp End Loop Dimensions: 4.8 x 2.7mm (approx.) (width x thickness)...
Category

Italian 21st Century and Contemporary Link Necklaces

Materials

Gold, 10k Gold, Yellow Gold

18 Karat Black and Yellow Gold Curb Necklace
Located in Dallas, TX
In 18 karat black and yellow gold, secured with a lobster clasp.
Category

21st Century and Contemporary Link Necklaces

Materials

18k Gold, Yellow Gold

Classic 14k Yellow White Gold 24" Diamond Cut Curb Cuban Link Chain Necklace
Located in Montclair, NJ
Material: Solid 14k Yellow Gold w/ White Gold Accents Weight: 29.52 Grams Chain Type: Diamond Cut Style Cuban Curb Link Chain Length: 24 inches Chain Width: 7.1mm (approx.) Clasp: Lo...
Category

21st Century and Contemporary Link Necklaces

Materials

Gold, 14k Gold, White Gold, Yellow Gold

Roberto Coin, 18K Yellow Gold and Diamond Station Necklace
Located in Chicago, IL
This gorgeous necklace by Italian designer Roberto Coin contains five round brilliant cut stations weighing approximately 0.25 carat total, suspended by cable link chain with an adju...
Category

Italian Contemporary 21st Century and Contemporary Link Necklaces

Materials

Diamond, 18k Gold, Yellow Gold

Superb 15.12 Carat Ruby Platinum Tennis Necklace
Located in Beverly Hills, CA
A tennis necklace featuring a straight line of super fine quality rubies. They weigh a total of 15.12 carats and what makes them so special is their color and brilliance. They have b...
Category

American 21st Century and Contemporary Link Necklaces

Materials

Ruby, Platinum