A 50.47-carat cushion brilliant-cut diamond ring is expected to be the top lot at Christie's Magnificent Jewels Sale in Geneva tomorrow. The D-color, VVS1-clarity diamond is set in a platinum ring designed by Harry Winston and carries a pre-sale estimate of $5 million to $7 million.

Christie's is saving the best for last. Bidding for the sale's headliner will culminate two sessions, during which 419 lots will hit the auction block at the Geneva Four Seasons Hotel des Bergues. The first session starts at 1:30 p.m. and includes Lots 1 through 274. The second session commences at 7 p.m. and covers Lots 275 through 419.

Christie’s boasts that its Magnificent Jewels Sale catalog reads as an encyclopedia of the world's finest jewelry. And while it's true that the auction house will be offering a range of spectacular pieces — including Art Deco, Retro and animal-themed jewelry — colored and colorless diamonds stand out as the highest-valued lots of the sale. Here are some of the most exciting items up for grabs...

Superb Diamond Ring, Harry Winston (Lot 419). The 50.47-carat cushion brilliant-cut diamond in this ring carries the ultra-rare Type IIa purity grade and is potentially internally flawless, according to Christie's. Estimated price: $5 million to $7 million.

Rare Colored Diamond and Diamond Ring (Lot 381). A fancy light purplish-pink rectangular cut-cornered diamond weighing 33.51 carats is the colorful centerpiece of this white gold ring. Flanked by tapered baguette-cut diamonds and secured by double-claw prongs, the fancy-colored center stone boasts a VS2 clarity. Estimated price: $4 million to $5 million.

Sensational Colored Diamond Ring (Lot 414). This fancy vivid yellow rectangular cut-cornered diamond weighs 20.49 carats and is set on a plain white gold band. The diamond earned a clarity rating of VVS1. Estimated price: $3.8 million to $4.5 million.

Colored Diamond Ring (Lot 406). Also boasting a clarity of VVS1, this fancy intense purplish-pink rectangular cut-cornered diamond weighs 8.52 carats. Estimated price: $3.5 million to $5 million.

Rare Colored Diamond and Diamond "Toi et Moi" Ring, Cartier (Lot 418). Translated in English as "You and Me," this stylish "Toi et Moi" ring by Cartier features a 5.03-carat fancy intense blue pear modified brilliant-cut diamond and a 4.16-carat fancy vivid yellow pear modified brilliant-cut diamond, connected by sweeping steps of yellow and colorless tapered baguette diamonds. Estimated price: $2.5 million to $3.5 million.

Diamond Ring (Lot 320). Scintillating 21.83-carat marquise brilliant-cut diamond highlights this platinum ring. The D-color gem has a clarity of VVS2, but is potentially internally flawless, according to Christie's. This stone also carries the coveted Type IIa purity grade. Estimated price: $2.5 million to $3.5 million.

Impressive Diamond Riviere Necklace (Lot 352). Exactly 26 graduated old-cut diamonds — the largest of which are 15.04, 13.20 and 13.02 carats — add brilliance to this choker-length necklace, which is fabricated in silver and gold. Estimated price: $1.7 million to $2.2 million.

Credits: Images courtesy of Christie's.