Setting stones in PMC is not without its problems; a lot can go wrong and it’s very much a case of trial and error until you discover what works for you and your work. Are you a beginner in jewellery making and you’re wondering how to set gemstones into precious metal clay? Discover how you can use these gemstone setting techniques in your own jewellery making projects.
The process of PMC stone setting
Stones react differently to heat, some can withstand it and others cannot, so it’s important to ascertain if the stones you are using can take a direct heat as this will determine the method you use to set them into metal clay. Most CZs with the exception of emerald green coloured stones can take direct heat, meaning they can be set directly into clay before firing. There are also ranges of PMC safe CZs and stones available, which should give you that extra peace of mind.
Remember that when you’re setting Swarovski® Zirconia stones they are different again, and contrary to popular belief, many can actually be set directly into PMC before firing (this has been verified by Swarovski®). With such a vast product range to choose from within the Swarovski® family, the general rule is that pinks and reds are likely to change colour during heating, whereas the other tones such as whites, blues and greens should survive OK. So, we decided to put this to the test.
A word of caution: if you are in any doubt as to whether your stone will survive heating, simply create a bezel and glue in after firing. All stones can be temperamental and anyone applying direct heat to any type of stone does so at their own risk.
What are the methods for setting gemstones in metal clay?
Here’s a step by step process of setting stones in metal clay:
- Simply push the stone into the clay ensuring the edges (girdle) are covered. This will work for smaller stones (1-2mm) if pushed far enough in.
- Push the stone into clay and using PMC in a syringe, pipe a bezel around the edge of the stone, ensuring the edges (girdle) are fully covered to allow for shrinkage. Smooth with a paintbrush and water as the piece is drying for a neat finish.
- Create a bezel from fine silver bezel wire and fire into place, setting the stone once the piece is finished.
- Create an indentation for your stone before firing, and glue the stone into place once the piece is complete. Remember that PMC shrinks during firing so make the space bigger than the stone to allow for this.
What about firing stones in metal clay?
We tried firing a selection of Swarovski® Zirconia stones into PMC3 to see what would happen, with some interesting results. Some of the stones did withstand the heat with no colour change or adverse effects, but as expected, others didn’t cope as well.
We torch fired the pieces for 1.5 – 2 minutes with a hand torch, positioning the stone face down into the heat brick. As with all PMC, you should heat the item until binder burns off, then gently move the flame until the piece starts to glow orange. At this point start your timer, and heat for between 1.5 – 2 minutes maintaining the orange colour, holding the torch approximately 6cm away from your item. If the item starts to turn silver it is beginning to melt and has overheated, so draw back a little.
It is important to cool stones slowly, so simply allow your items to cool down in the air and never be tempted to quench. Once the pieces had dried out overnight, we cleaned them up using an emery board and a cocktail stick!
We found the cocktail stick was great for gently running around the edge of the stone to create a neat edge, and the emery board was ideal for general smoothing and rounding off. Finally, simply buff to finish using a scratch brush and glue the remaining stones into place.
Here, you can see some of the Swarovski® Zirconia stones which were fired in the clay, and as you can see some are OK and some are not. The Square Princess Pure Brilliance Cut 4x4mm in Fancy Blue (product code 6SZB 40C), the Round Pure Brilliance Cut 5mm in Green (product code 6SZA 50E) and the Round Pure Brilliance Cut 7mm in White (product code 6SZA 70A) survived with minimal colour change. The Oval Pure Brilliance Cut 6x4mm in Red (product code 6SZE AHF) changed colour dramatically however.
Here, you can see the stones which were glued in after firing, thus experiencing no colour change.
Top tips to remember when firing stones in metal clay:
- Stones are temperamental and nothing is guaranteed, so be open minded and experiment – some things might work and others may not. It is always best to do some tests before jumping into the final piece.
- Always place stones face down when heating.
- Always cool stones slowly.
- Allow for shrinkage when creating stone indents pre-firing (PMC3 is approximately 10% shrinkage).
Feel ready to try setting a Swarovski® Zirconia stones into precious metal clay? Why not get started by browsing Cooksongold’s latest range of Swarovski Gemstones™ alongside our selection of PMC clay today.
Still a little unsure where to start when it comes to setting Swarovski and other gemstones? Order Cooksongold’s handy guide on ‘The Art of Metal Clay’, where you can follow through the process of PMC stone setting.