For many years there’s not been a well-accepted terminology for the
clear Mexican opal material. The Mexicans used to call it ‘water
opal’ and then ‘crystal opal’. I confuse about half of my clients
calling it one or the other. ‘Any ideas from the group on what the
best nomenclature would be? I have quite a supply, including the
’Fire opal’, which also causes confusion to some since both types
are VERY scarce anymore, with most mines having been shut down for
several years. "Fire opal’ actually is an orange-to-red colored base
and, if high quality, also has the green/red/blue ‘fire’ of natural
opal material. See some photos on my site to get the idea,
kirk