CVD experts: are Frankenstones possible?

[MelloYello8]

After reading some speculation that lab diamonds may give rise to experimentation in cutting, I wondered if experimentation could be done on the growth of a diamond itself. If CVDs are made with a seed diamond, can that seed potentially be a different color or shape of what it grown around it? For example can a little red diamond be grown and cut into a heart shape, then used as a seed for a bigger white diamond so a little red heart would be embedded into an emerald cut white diamond? What about changing the environment somewhere in the growth process, like a vacuum at first so the diamond initially starts growing white, but replace it with boron so the subsequent growth is blue- like a gobstopper. Then when the rough it cut, there would be different colors in different facets instead of color uniformity.

Obviously I’m woefully ignorant of the lab diamond process, but it seems like a fun idea.

 

[EEFranklin]

The seed can certainly be a different color. Some CVD growers use yellow HPHT-grown diamonds as seeds, though it is a thin (<.3mm) plate and is entirely removed during polishing. I don't see why they couldn't use a thicker yellow or blue HPHT-grown diamond. Pink, red and green are usually made by post-growth treatment and the temperatures in a CVD reactor would likely make those colors unstable if used as seeds.

For the most part, CVD grows straight up from the seed plate, so it wouldn't "snowball" around a red heart, just grow diamond directly above that heart. The faceting would likely cause problems, and you would probably have separate diamonds growing from each facet, if they would even grow on non-flat surfaces.

The blue color comes from boron, which is easy in HPHT, but mostly experimental in CVD. The yellow color comes from nitrogen. Theoretically, it could be possible to adjust the impurities in the gasses during the CVD growth process to alternate between white, blue and yellow flat color stripes. In practice it isn't as easy as turning a couple knobs or dials, and probably isn't something anyone would offer as a special order.

 

[OoohShiny]

I like your thinking, MelloYello!

I remember seeing a diamond at one of the London museums (the Natural History Museum, I think?) that had a red-colour stone within it - I can't remember what the other stone was now, but it was cool to see it actually on/in the diamond

 

[MelloYello8]

The seed can certainly be a different color. Some CVD growers use yellow HPHT-grown diamonds as seeds, though it is a thin (<.3mm) plate and is entirely removed during polishing. I don't see why they couldn't use a thicker yellow or blue HPHT-grown diamond. Pink, red and green are usually made by post-growth treatment and the temperatures in a CVD reactor would likely make those colors unstable if used as seeds.

For the most part, CVD grows straight up from the seed plate, so it wouldn't "snowball" around a red heart, just grow diamond directly above that heart. The faceting would likely cause problems, and you would probably have separate diamonds growing from each facet, if they would even grow on non-flat surfaces.

The blue color comes from boron, which is easy in HPHT, but mostly experimental in CVD. The yellow color comes from nitrogen. Theoretically, it could be possible to adjust the impurities in the gasses during the CVD growth process to alternate between white, blue and yellow flat color stripes. In practice it isn't as easy as turning a couple knobs or dials, and probably isn't something anyone would offer as a special order.

Thanks for your insightful thoughts. Are the diamonds grown inside some sort of cookie cutter that determines their outer limits of where they grow? I kind of like the idea of separate diamonds growing out of different facets. Like a diamond chia pet. If I understand it now, a faceted diamond seed might grow multiple arms and if done just right, the arms could be cut to make it look like a 3D star; or if in yellow, the sun.

 

[EEFranklin]

The cookie cutter is the thin slice or plate of diamond used as the "seed", which provide the crystal structure to form one larger diamond. The diamond grows basically straight up from that plate, however the edges are not clean and usually have black polycrystalline diamond all around (think bumpy black unusable edges). This is typically cut off with a laser, then the diamond is polished like normal from the lasered cube or cylinder into the desired gemstone.

If a faceted diamond could be used as a seed (a big if), growth on a parallel table facet would probably be okay. Carbon might just slide off of the angled facets, but if it did grow, it should grow straight up, not perpendicular to the facet. Assuming new diamond grew above all the facets, the best case outcome would look like all the facets were outlined in black (the polycrystalline diamond), with a smaller transparent window of diamond into each facet below. The overall diameter of the diamond wouldn't change much, just the thickness. It likely wouldn't look nice, and may be a fun experiment, but wouldn't end up as a pretty star with clean arms radiating from the center.

 

[MelloYello8]

Thanks for entertaining my crazy.

What if each arm was grown individually instead of concurrently, rotating the seed diamond to expose a different facet to be used as a plate each time? Assuming of course there was a way to accommodate the already formed arms and keep them out of the way.

 

[EEFranklin]

Even if you could properly mask the other facets and rotate it over many growth cycles ($$), the result would still be a rough diamond with black polycrystalline diamond around all the edges. It wouldn't be a ready-to-wear starburst, and wouldn't be able to be polished in a normal manner. This 'arm' concept might be theoretically possibly, but would be a massive R&D project. It isn't easy, practical or cost effective.

 

[OoohShiny]

This is a terrible quality but useful video! lol

 

[MelloYello8]

Even if you could properly mask the other facets and rotate it over many growth cycles ($$), the result would still be a rough diamond with black polycrystalline diamond around all the edges. It wouldn't be a ready-to-wear starburst, and wouldn't be able to be polished in a normal manner. This 'arm' concept might be theoretically possibly, but would be a massive R&D project. It isn't easy, practical or cost effective.

Maybe it isn’t cost effective now, but if and when there is increased demand for lab diamonds, the technology is faster and cheaper, and more labs enter the market, maybe there would be interest in creating novel rough stones to stand out from a crowd?