A colour name is not a mineral identity
Ask what material is being offered and whether it is natural, laboratory-grown or an imitation. For example, a Paraiba-colour description does not by itself identify Paraíba tourmaline. Put the material and origin in the written specification.
Look at hue, tone and saturation
Compare the colour in more than one light source. Camera exposure, white balance and the screen can change the impression. Request neutral-light images and a moving view of the actual stone rather than relying on a promotional photograph.
Cut, clarity and use
Check the stone's outline, dimensions, visible inclusions and how evenly it presents colour. Some features may affect durability or the way it should be set. Ask a jeweller to assess whether the material and setting suit the intended wear.
Confirm treatment and care
Ask what treatments are known and what documentation supports the description. Cleaning advice depends on material and treatment, not colour alone. Agree the individual stone, price and delivery before placing an order.
Sources and further reading
This English edition draws on the source material referenced below.