A popular Moldavite retailer used to have a great article on spotting fake Moldavite that included some great examples. The website has since gone dark, but fortunately I was able to recover the article. The following is a verbatim reproduction of the "How to Spot Fake Moldavite" page from Harusami and Soul2Soul Treasures. The only changes I've made are to the book links.
Fake Moldavite Part 2 | How to Spot Fake Moldavite
And if you haven't already, be sure to check out Part 1.
Fake Moldavite | How can I tell if Moldavite is real or fake?
