At the New York headquarters of Cora International LLC, Suzette Gomes is spellbound by a sight of rare beauty.

“You can’t describe that blue,” said Gomes, chief executive officer of the diamond-cutting company. “You just drown in it.”

“That blue” refers to the Blue Moon diamond. Cora paid $25.6 million for the uncut, 29.6-carat stone in February.

Colored diamonds are the world’s most expensive stones. A 14.82-carat orange diamond sold for $36 million at Christie’s International in Geneva in November, setting a record $2.4 million a carat. The same month, Sotheby’s sold the Pink Dream, a 59.6-carat pink stone, for $83 million.