Questions to ask when buying an Opal

It is important that you receive accurate and complete information from your vendor.
For example, you need to clarify whether a stone is a natural solid, composite(doublet or triplet) or synthetic and whether it is a light, crystal, dark, black or a boulder Opal.

The vendor should be able to supply a certificate confirming the authenticity of the stone in relation to these features, the weight, dimensions and the purchase price.