Aventurine Marron is the Italian name for a specialty glass the Americans call Goldstone. Before I got into lampworking I would see cut stones and beads made out of goldstone in lapidary shops and I have always thought it was really cool looking glass.
Frantz Art Glass buys its goldstone/aventurine from Effetre, but on one trip to Murano, Italy we found out that Effetre didn’t actually make the goldstone, but instead was a middle man for another glass company. This lead us on an adventure to find out where and how it was made because we were looking for a source for larger chunks (fist size boulders), so that we could offer a larger range of goldstone piece sizes.
The formula for making adventurine /goldstone has been a much guarded secret through the ages in Europe. The story goes that it was originally developed by glass making monks, but I can’t say how accurate this charming tale is. I know for sure that the goldstone we buy from Effetre is made in a glass factory in Northern Italy.
One of the reasons that this particular type of glass is so expensive is the fact that when they make a crucible of goldstone, only one third of the batch is “A” quality with the familiar bright flakes in it. The other two parts of the batch are “B” quality that has a lot of veins of brown in it and the last third is waste and they have to break the crucible off the glass when it has cooled, so they lose the crucible ever time they make a batch and crucibles are expensive.
You can get goldstone/aventurine to use in five sizes from powder to large chunks that you can use as is or process into what ever stringer or cane you like. Last year we were fortunate to obtain a batch of specially made goldstone ribbon cane that was made by a glass artist that we know on Murano. Recently we received another batch of ribbon cane and this batch is really great! It is thicker, brighter and easier to use than the last batch and I have been enjoying using it.
The ribbon cane is really nice to use because it has a very thin coat of clear glass over the goldstone which keeps the ribbon cane looking brilliant even when exposed to high heat. I learned the hard way that to get goldstone from pieces to look bright after being torched, it is best to have a thin layer of clear glass over it. When I first started messing around with goldstone, I would have the raw goldstone in the flame and it would turn kind of khaki brown-green with almost no sparkle to it – very disappointing!
Aventurine/goldstone comes in a few other colors which the most common are blue and green, though I have seen red goldstone in the past. You have to be careful with the really rare colors of goldstone because sometimes it is not compatible.