Round

The most popular shape with brides, the round-often called the round brilliant-has triangular facets, arranged to direct light from the bottom of the stone up through the top for maximum sparkle. Matt Damon proposed to Luciana Barroso with a three stone round diamond ring.

.30-carat diamond in 18kt white gold, Mauboussin, price upon request; 212-752-4300.

3.85-total-carat-weight diamonds in platinum, Harry Winston, price upon request; 800-988-4110 for stores.

1.5-carat brilliant-cut diamond and .57-total-carat-weight side stones in platinum, Scott Kay, $19,700; scottkay.com for stores.

1-carat diamond in platinum, Harry Winston, price upon request; 800-988-4110 for stores.

1.04-carat diamond in platinum, De Beers, $12,000; debeers.com.

1.16-carat diamond in platinum, Kwiat, $6,750; kwiat.com.

.75-carat diamond in 14kt yellow gold, Doyle & Doyle, $3,800; doyledoyle.com.

1-carat Bezet diamond in platinum, Tiffany & Co., $9,200; tiffany.com.

2-carat diamond in platinum, Tacori, price upon request; tacori.com.

.85-carat sapphire with .54-total-carat-weight diamonds in 18kt white gold with rhodium finish, Charles Perrella, $2,925; clay-pot.com.

Diamond and .31-total-carat-weight pave diamonds in 18kt white gold, Simon G., price upon request; simongjewelry.com.

3.02-carat brilliant-cut diamond and .71-total-carat-weight tapered baguettes in platinum, De Beers, $255,000; debeers.com.

.3-carat brilliant-cut diamond in platinum, Bulgari, price upon request; 800-285-4274 or bulgari.com.

2.3-carat brilliant-cut diamond in 24kt yellow gold, Gurhan, price upon request; 602-955-8000.

Diamond and 1.22-total-carat-weight white and yellow pave diamonds in 18kt white and yellow gold, Simon G., price upon request; simongjewelry.com.

.3-carat brilliant-cut diamond and pave diamonds in platinum, Bulgari, price upon request; bulgari.com.

Custom diamond in platinum, David Yurman, price upon request; davidyurman.com.

1.5-total-carat-weight ideal-cut diamonds in platinum, Blue Nile, $7,200; bluenile.com.

.50-carat diamond and .24-total-carat-weight side stones in platinum, Suzanne Felsen, price upon request; suzannefelsen.com.

1-carat round diamond and .30-total-carat-weight pave diamonds in platinum, Tacori, $8,460; tacori.com.

.60-carat diamond in platinum, Tiffany amp Co., $3,925; Tiffany.com.

1.5-carat rose-cut sapphire in 18kt yellow gold, Donna Distefano Ltd., $2,200; donnadistefanoltd.com.

1.11-carat cognac diamond with .13-total-carat-weight diamonds in yellow gold, Suzanne Felsen, price upon request; suzannefelsen.com.

2-total-carat-weight diamonds in 18kt white gold, Donna Distefano Ltd., $15,000; donnadistefanoltd.com.

1-carat round brilliant-cut diamond in platinum and 18kt yellow gold, Tiffany & Co., $9,350; tiffany.com.

.25-carat diamond in 18kt yellow gold, Dawes Design, $2,400; dawes-design.com.

1-carat round diamond and .50-total-carat-weight marquise diamonds in 18kt white gold, Simon G., $2,090 (not including center stone); simongjewelry.com.

1.1-carat rose-cut diamond and .55-total-carat-weight Old European-cut diamonds in platinum, Karen Karch, $12,445; karenkarch.com.

.44-carat brilliant-cut diamond and .34-total-carat-weight side stones in platinum, Richard Landi, $5,620; clay-pot.com.

.63-carat diamond in 18kt yellow gold, Marian Maurer, $4,620; clay-pot.com.

.50-carat diamond and .80-total-carat-weight diamonds in 18kt white gold, Roberto Coin, $8,400; 800-853-5958 for stores.

1-carat diamond and 1.68-total-carat-weight diamonds in 19kt yellow gold, Scott Kay Vintage, price on request; 800-487-1584.

.3-total-carat-weight rose-cut diamonds in 18kt yellow gold, Me & Ro, $1,665; 917-237-9215.

.50-carat diamond in platinum, Doyle amp Doyle, $2,950; doyledoyle.com.

1.25-carat diamond and .30-total-carat-weight pink diamonds in platinum and 18kt rose gold, Tacori, $5,070 (not including center stone); tacori.com for locations.

0.44-total-carat-weight diamonds in rose gold, De Beers, $6,000; debeers.com.

1.37-carat brilliant-cut cognac diamond and .29-total-carat-weight marquise-cut diamonds in platinum, Suzanne Felsen, $13,575; suzannefelsen.com.

.25-carat round-cut diamond in 22kt yellow gold, Annie Fenerstock for Fragments, $3,405; 212-334-9588.

.44-total-carat-weight pave diamonds in sterilng silver, John Hardy, $1,495; 866-454-2739.

1-carat round-cut diamond and pave diamonds in platinum, Neil Lane, $15,000; 310-275-5015.

2-carat mandarin garnet in 18kt white gold, Suzanne Felsen, $3,500; 310-315-1972.

1.08-carat diamond and .72-total-carat-weight diamonds in platinum, Christopher Designs, $21,100; 800-955-0970 for stores.

.44-total-carat-weight diamonds in 18kt white gold, Kwiat, $1,600; kwiat.com.

.60-total-carat-weight diamonds in 14kt white gold, Doyle amp Doyle, $975; doyledoyle.com.