These are Corallium Elatius corals.
 An exceptional grade of coral, amazing shean, beautiful shade...
 
 What a great give to offer to someone... 
Here are the sizes, by now you have picked up ideas what you can achieve with these umounted cabochons.
 
Centre cabochon size: 19.5 x 13.5 x7mm 
 Weight: 4 grams.
 
Two cabochons pieces
Size: 15 x10 x4mn
Weight: 2.3 grams