I hope that I got the chance to meet you at YCMI this year
I thought long and hard about what to give everyone in the goodie bag that would be useful and worthwhile and I decided on some fireable gemstones. As you will no doubt already know, most natural gemstones cannot be torch or kiln fired. This is because they have natural fissures and cuts in the stones and the heat expands in these cuts and smashes the stone.
There are some natural stones that can be fired and you can find details of these in this excellent resource from Cool Tools
Why choose synthetic gemstones?
'The general characteristics of a synthetic stone are the same as those of natural material but being laboratory produced, they tend to be clearer and finer than natural equivalents'
For me there are benefits of buying a synthetic or lab created gemstone
it can be fired with a torch or in a kiln
mining gemstones from the earth has negative environmental and human impacts, these are avoided when using synthetic stones
synthetic stones are clear and have the exact same properties as mined natural gemstones
Where can I buy synthetic/lab created gemstones?
I bought these stones from Manchester Minerals and I recommend them for the quality of their stones and their great service. They also stock synthetic sapphires and spinel. I have successfully fired the sapphires but haven't yet tried the spinel.
How can I test stones that I've bought to see if they can be fired in metal clay?
Before you spend time (and money!) on setting gemstones that you've bought from a new supplier you should heat test them
If you have a kiln - place them in the kiln and heat them at the same temperature as suggested on the brand of clay you will be using
How do I set faceted fireable stones?
There are some rules for setting fireable stones in your work successfully
The table (top) of the stone needs to be level with the top of the metal clay (see diagram 2). This is because of the shrinkage of the clay. If the stone is not pushed all the way into the clay, when it is fired the shrinkage can pop the stone out. Ensure that the stone is level and cannot be seen protruding from the clay when you hold the piece at eye level
I have found for a 3mm round stone that 7 or 8 playing cards is the right thickness
To test the thickness you need for a stone - put your gemstone down with the culet (point) facing up. Lay a playing cards each side of the stone. Lay a playing card on top of the stone and see if you can feel the point protruding through the card. If you can still feel the stone you will need more playing cards. If not, count how many cards you have each side and use that amount to make a piece to set your stone
After firing, allow the piece to cool naturally, DO NOT quench the piece in water. Going from hot to cold water can shatter the stone
Share your makes!
I would love to see what you make with the stones. Please do tag me on instagram @annaccampbell or email me photos
Here are some of the pieces that have been made with the stones. Gorgeous aren't they?