What is the difference between diamond stud and solitaire?

The main difference is in the type of jewelry and how the diamond is used:

Diamond Stud: Typically refers to earrings with a single diamond in each earring. It's a style of earring.

Solitaire: Refers to any jewelry piece (most commonly a ring) that features a single diamond as the main centerpiece. The term "solitaire" highlights that there's just one central stone, with no side stones.

So, "diamond stud" is about earrings, while "solitaire" is about the design style of a single-stone jewelry piece, usually a ring.