How it Works: Recutting Gems to Maximize Value

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PinkDiamond
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How it Works: Recutting Gems to Maximize Value

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Good stones often come to us with really bad cuts usually done to maximize size, at the expense of beauty. For those who own faceting machines, this will show you how to recut gems with inferior cuts yourself, to maximize their beauty instead of their weight. For those who can't recut their own stones, there are videos at the end of the story that will show you the difference before and after recutting, so you'll know why you might want to have it done to some stones. Enjoy! :)

How it Works: Recutting Gems to Maximize Value
by Daniel Stair

Image
5.24-ct spinel before recutting. © Dan Stair Custom Gemstones. Used with permission.

In other articles, we’ve discussed how custom cutting from rough can make a big difference in a gem’s optical performance. We’ve also covered how recutting diamonds and colored stones can help repair damage to gems. Now, we’ll demonstrate how a skilled lapidary with proper equipment can take an average or even below-average poorly cut gemstone, whether native or commercially cut, and make it into something truly special, compelling, and valuable.

Longtime International Gem Society (IGS) member Daniel Stair will show us how recutting gems works. Starting with a commercially cut mixed oval 5.24-ct spinel, he’ll walk us through the process.


A Standard Cut Gone Wrong

"Gem cutters use the standard mixed cut for most all gem shapes. It consists of a step-cut bottom (pavilion) and a brilliant-cut top (crown). Step cutting is done using rectangular or square-shaped facets. Brilliant cutting is done using triangular, diamond, and/or kite-shaped facets.

Look at the spinel at the top of this article. It’s a prime example of some great gem material poorly cut.

The Facetron

I’ll recut this gem using a Facetron faceting machine, probably the most popular faceting machine for custom gem cutting. Look at the photo below as I describe its features.

* To the upper left, you’ll find a water tank that drips water coolant onto the spinning lap (cutting or polishing disc) below. This flushes away debris during cutting and helps to keep the gemstone cool.

* Below the tank, I’ve placed a polishing lap. It sits inside a silicone dish designed to stop water and debris from flying all over the cutter, wall, etc. The dish has a drain hose connected to a container that catches all the water, etc.

* To the right, you can see a mast that holds the faceting machine head. The head is used to control angle, rotation, and depth of each facet as it’s cut.

* You can adjust the angle on the right using the silver hand crank. The little window next to the crank displays the angle.

* The rotation of the arm is adjusted using an index gear. It’s divisible by the number of sides of the finished stone. You can see the gear at the top of the arm, just below the dial gauge for controlling facet depth.

* Front and right, you can see the on/off switch and the dial for adjusting the lap’s rotation speed.

Image
Facetron faceting machine. © Dan Stair Custom Gemstones. Used with permission.

Preparing the Gem

Before recutting gems, wipe them off with an alcohol swab. This will remove all traces of oil present on the surfaces.

Image
Wiping off the stone with alcohol. © Dan Stair Custom Gemstones. Used with permission.

Next, attach your stone to a flat-ended dop stick keyed to fit into the end of the faceting machine’s arm. To do this:

* Heat up the brass dop using an alcohol burner.
* Wipe off the old wax.
* Put the dop into a block of new wax and get a nice gob of melted wax stuck to the end of the hot dop stick.
* Stick your stone on the melted wax end of the dop stick.

This will hold it in place during cutting and polishing.

Image
Heating the dop. © Dan Stair Custom Gemstones. Used with permission.

Image
Wax going onto the dop. © Dan Stair Custom Gemstones. Used with permission.

Use a transfer jig with a ... "

https://www.gemsociety.org/article/recu ... =igs_email
PinkDiamond
ISG Registered Gemologist


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