What is a Doublet in gemology?

• A. Two pieces of material fused or cemented together to form a single assembled stone.
• B. A natural diamond with a synthetic core.
• C. A diamond with a surface coating.
• D. A lab-grown diamond.

Answer: (A)

A doublet is a gemstone made from two separate pieces that are joined to behave as a single stone. Typically a thin top layer of the desired material is bonded to a backing made of a different, usually cheaper, material, and the two are fused or cemented together. This creates the appearance of a larger or more color-rich gem while using less of the high-cost material. In practice, you might see a visible interface between the two layers under magnification or certain lighting, which reveals its composite nature. The other options describe different situations—two-part construction is not about a natural diamond with a synthetic core, a diamond with a surface coating, or a lab-grown diamond—so they don’t fit the idea of two pieces permanently joined to form one stone.