How to Cast Gem Stones in Place Tutorial

These rings were cast and polished during  this demonstration on how to cast stones in place.

We started  with 2 each our 12 piece assortment of lightweight 4x6 ladies oval rings pictured above. These waxes have "prenotched" heads to hold the stones. These prenotched heads make it easy to cast stones in place.  The "prenotched" means that the seats are already cut to hold the stones. 

Under normal stone setting procedure, small "heart" burrs aka 45 degree bearing burrs are used to cut the seats into the prongs. The stones are placed inside the prongs and then gently tightened around the stones using small pliers.

The wax rings we are using already have the seats cut in place, so 95% of the setting work is done.

First we laid out the waxes and stones and carefully placed  them into the prongs

Make sure the stone is setting in the "notches"

You can also lay the stone on the table and gently press the stone into the prongs

Once the stone is sitting in the notches, gently press the prongs against the stone, this tightens the prongs and helps form the seat to hold the stone. Be gentle but firm.

In a few minutes all the stones are in place and ready to cast

Now we follow normal casting procedures, sprue and build tree on a sprue base

Invest as normal

 After the investment sets up in about 45 minutes we are ready to burnout.

We  Burnout at 1100 degrees instead of 1300 degrees. The reason we burn out at a slightly lower temperature is because some stones are "heat treated" to enhance their color. The higher the burnout temperature, the more the possibility you can change the color, so burnout as low as possible. 1100 degrees seems to work fine for most stones.  We had a couple of the stones change color during this session,  More on that later.

You may need to extend your burnout time a little bit longer because you are burning out at a lower temperature.  A good friend that does a lot of casting diamonds in place,   burns out out at 900 degrees for 12 hours.  He claims 900 is better than 1100 degrees  and reduces the risk of "burning" or "fogging" diamonds.  He says in the past year he has 100% success rate casting diamonds in place when the burnout is 900 degrees.

 I say, experiment and stick with the results that works best for you.  Again, we suggest burning out as low as possible, but make sure the flask is completely burned out before casting.

 Burnout is complete when the investment is chalky white and the sprue holes are glowing orange. If there is any grey or dark residue in the sprue holes, extend your burnout time until the investment is chalky white.  Don't cast until completely burned out. It can cause porosity and incomplete castings.

Cast as you normally do, flask temp should be between 800 - 900 degrees when casting takes place. 

The secret to casting stones in place happens after casting.

Let the flask "bench cool" for a minimum of 1 hour before devesting. Do not quench the flask when it is hot,  the sudden temperature change  will fracture the stones.

 Wait a minimum of one hour.

 This flask took 1 1/2 hours before it could be handled

We use a rawhide mallet or rubber mallet and tap on the flask until the investment begins breaking away.

Keep Tapping until the casting breaks loose.

 use a dental tool or pick  to help remove the investment.

 Do not devest using a bead blaster or sand blaster, it will pit the stones.

Into the sonic cleaner for a bath, if you don't have a sonic cleaner, scrub with a tooth brush. (sonic cleaner is easier)

This casting did not need pickling, however You can pickle castings to remove oxides if necessary,  it will not hurt the stones.

Now your ready to polish your new jewelry.

For those not familiar with stone setting. The above "cup" bur fits into your flex shaft and is used to shape the top of the prong. They are very simple to use, the cup is placed on top of the prong and you rotate the cup over the top of the prong.  It makes the tops of  all 4 prongs exactly the same size and shape. We used a 1.6mm cup bur for this demonstration.  They are available at your local jewelry supply store. If you can't find them, we sell them for $2 each or 6 for $7.95 (sorry about the plug) but they are very handy little burs and we suggest you use them if possible.

A couple of notes. 

The "mini Swiss" CZ  is a beautiful blue color. When we cast it in place it turned into an awesome looking deep emerald color.

The "Tanzanite" CZ is also a gorgeous color, It turned into "Smokey Topaz". It looks great but isn't "tanzanite" color anymore.

One customer informed me that the Black CZ's changed colors on him, but he burned out at 1300 degrees instead of the 1100 degrees we recommended.  We have not had his problem with the black cz's at 1100 degree burnout temperature. Just a heads up to be aware the black may change color at higher burnout temps. 

Another suggestion would be to burn out at 900 degrees to help keep colors intact. We also suggest burning out at 900 degrees when casting diamonds in place to help reduce the chance of "fogging" or "burning" the diamonds.

We highly suggest "easing" into this process. Don't load up a flask with a lot of stones your first time around. Practice and experiment until you feel comfortable using this process.  There are a few more tips at the bottom of the page.

We will be glad to answer any questions you may have, just email help@waxpatterns.com  and we will try and point you in the right direction.

If you would like to try casting stones in place. Try these starter kits below. These lightweight rings and pendants are some of our most popular designs and with the pre notched prongs, it makes setting a "snap".

12 Piece Pre Notched Ring Assortment

12 Piece Pre Notched Pendant Assortment

 Pre Notched Heads

4 prong heads with post. Seats are already cut for stones. Makes setting stones a "snap" Great for casting stones in place. Perfect for adding small accent stones to any wax. Eyes for animals, mothers rings, anywhere you want to add a stone. Use post to help position in wax, poke or drill a small hole and place post through hole, blend/melt head into position. Can be added to any wax design.

Wax "Pre Notched heads"  available in 1.75 mm, 2mm, 2.5 mm, 3mm.

Stones available in over 1,000 different sizes and shapes and colors, we have  lots to choose from. 

Visit our Gemstone  page.

Cup Burs

for Finishing off prong tips

One last note. You can use any wax pattern to cast stones in place.  You will need to make small notches in the prongs using a scalpel, exacto knife or mold cutting knife, or a small heart bur.

As long as your stone is firmly held in place by the wax, you should be ok. When setting bezels, make them a lose fit, you get about 7% shrinkage during the casting process and the shrinkage can squeeze the stone and fracture it.  Also make sure you can see the top and the bottom of the stone, if the wax is covering the bottom of the stone,  the stone will fall out when the wax is burned out, the investment can not hold the stone in place.  A class ring is a good example of what you cannot do. No way for the investment to hold the stone in place.  Good luck and have fun casting stones in place.