I've never made doublets before, but I'd like to try.

My concern is that I don't have a flat lap. I only have a trim saw, and a 6-wheel Diamond Pacific Genie.

Is it possible to attach the dome to a backing without using a flat lap to grind them smooth? If so, how do I ensure a proper fit before applying the epoxy?

I'd like to be able to use a variety of materials for the doublets, ranging from very soft (like opal) to hard (like agates) (e.g. opal with quartz domes, plume agates with turquoise backings, etc.).

2 Answers 2

  • It seems that, according to their website, your Diamond Pacific Genie is able to flatten and polish gemstones using the "right hand wheel" as a platform for, e.g.,

    "Lapcraft "No Hole" discs [like this one]. They screw into the right hand wheel adaptor of the Genie, giving you a 6" diameter lap with no bothersome center hole."

  • You could also look into exchanging your trim saw blade with a polishing stone, something that is probably dependent on the model and type of connection.
    Not to mention that it can be dangerous, as trim saws have different speeds and were designed for different pressure types and lighter attachments.
    Try at your own peril :)

  • There is also a multitude of tutorials on homemade flat lap machines available online.

Although I have no experience with gemstone crafts, and contrary to rebusB's answer, I suspect two not completely flat surfaces will bond perfectly fine and invisibly when using the right bonding: a slow-curing epoxy might work, or G-S Hypo Cement, with which - provided they can be made fluid enough to fill even the smallest visible imperfections - you will be able to join the compounds without a clear visual boundary. As long as the bonding is clear and as thin as possible, I don't think this will be very obvious. You can heat up the glue a little to get rid of air bubbles, as mentioned here.
It's hard to find anything to back up this claim, though, so I suggest trying it out with inexpensive materials (some pieces of glass, perhaps, as this will make any imperfection readily visible).

Lastly, as a friendly reminder: be sure to wear respirator masks when polishing. You don't want metal fume fever, silicosis, or similar illnesses.


A doublet in this case being faux gemstone composed of two bonded layers of different materials, usually glass supporting a softer rare stone. You would need perfectly flat surfaces on the bond to get this to work, so if your tools cannot provide that then the answer would be no.

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