Ruby, sapphire and emerald: a first guide

Identify the gem

Ruby and sapphire are varieties of corundum; sapphire is not limited to blue. Emerald is a green variety of beryl. A trade colour name alone may not identify the material.

Ask about origin and treatment

A treatment does not automatically make a stone an imitation, but it can affect value and care. Ask whether the stone is natural or laboratory-grown and which treatments are disclosed. A photograph cannot reliably reveal all treatments.

Compare and care appropriately

View stones in different lighting and compare dimensions, not only weight. An appropriate laboratory report can help with valuable purchases. Follow care instructions for the specific stone and treatment rather than treating all coloured gems alike.