Boulder Opal Value & Characteristics: A Comprehensive Guide

Question
I have a necklace thats supposedly a boulder opal from australia? Are they worth anything? Its pretty good sized about the size of a thumb nail its diamond shaped set in silver and hangs inside a diamond shape made of silver as well. Thank You

Answer
Hi Laurel,
Boulder Opals can be very very valuable. What colours do you see , does it have a clean face ? there are any cracks or sand spots ? is the base colour blue ? green ? Red is a rare colour so if it has some red ...it worth being very nice to it ...but Laurel ,its just too difficult to tell or identify it without seeing it ... it sounds nice ...do you like it ?   best regards Rod Keady