I purchased a large silicone diamond mold (1 1/2" diameter) and have made several diamonds, but each time the part of the gem that is in contact with the mold does not look shiny. It is a 2-part mold, and looking down into the mold when filled with isomalt, it is clear as it can be. But when you remove the gem, the part in contact with the mold is not shiny and almost looks pitted. I have tried spraying the mold and not spraying the mold with Pam. I did contact the seller, but no help there.
Silicon generally will "gas" when it comes into contact with really hot sugar. This causes the pitting. You should be able to carefully take a torch and clean it up.
Thanks, I'll give that a try.
It worked! Thanks for taking the time to answer. You have saved me a lot of banging my head against the wall.
And for those who don't have a torch, steamer also works.