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Techniques for CollectorsFaceting Rhodochrosite

17th May 2009 00:44 UTCAnonymous User

I recently acquired a piece of gem grade Rhodochrosite, 8.5 ct., 90% clean and dog tooth crystal form. I would like to hear from any facetors that have cut this stone, problems with cutting & polishing, doping, etc. Does it need to be oriented? I think that I will use a round design for maximum yield. Being a soft stone I am planing to add it to my facet collection.

17th May 2009 01:11 UTCAdam Kelly

Good luck, I had lots of trouble polishing rhodo.

I was using aluminum oxide, and think I had the stone oriented wrong.

A round stone would be good, because there are no corners to chip.

I gave up, and just started setting loose rhombs in pendants.

Someone told me they were harder to polish because they are triagional crystals?

AK

18th May 2009 22:45 UTCGary Weinstein

Ron,

The hardest part is that they are so soft. Have you tried to polish calcite? Also they tend to cleave as easily as calcite does. Best to try on a less expensive piece first and experiment with speeds and laps/polish. I heard the mylar impregnated with tin work well. I have always cabbed rhodo with diamond and polished tin on leather or 50.000 dia. on cloth.

Hope this helps,

Gary

19th May 2009 18:07 UTCAnonymous User

Thanks! The softest that I have cut is Mexican Fire Opal and Fluorite.I think that I will take your advise Gary and practice with calcite.

20th May 2009 03:26 UTCHenry Barwood

Any rhombohedral carbonate (calcite, rhodochrosite, etc.) must be oriented so that NO cleavage face is parallel to a face on your stone. It is nearly impossible to polish a face parallel to a good, or perfect, cleavage. Good luck with your stone.

Henry Barwood

20th May 2009 09:35 UTCAlessio Piccioni

Hi Mr. Blattman, my friends many years ago cut a big calcite. He polish calcite with diamond powder and oil, on wood lap at slow velocity.

The problem is cleavege, dopping, you don't use a flame because carbonate are heat sensible, and when you polish is possible that the angle facet maybe round.

21st May 2009 00:28 UTCAnonymous User

You guys have been a great help. Thanks!

10th Jul 2009 08:43 UTCRay Hill Expert

I have a number of Rhodochrosites facetted in my gem collection and they aren't easy to cut.. as already commented..they are similar in hardness and cleavage and parting too , to calcites which are not easy to polish...SLOW COOL and CAREFUL are the key words and especially listen to Allessio, as he is right on the money regards heat...use epoxy and then dissolve later with acetone totally paying attention to the angles of cleavage and avoiding them . Practicing on calcite is a perfect playground in preparation to cutting Rhodos, since there are far fewer good facettable Rhodos than calcites.

10th Jul 2009 11:24 UTCSimone Citon Expert

Do not cut the Rhodo crystal, sacrilege!

10th Jul 2009 11:36 UTCAlessio Piccioni

Why Simone?

If i say you that i cut a phosgenite?:D What you say me?:D

Ciao Alessio

10th Jul 2009 11:53 UTCSimone Citon Expert

depends, if it was a well-formed crystal, you have done a sacrilege, if it was an insignificant mass, you have done well (for your collection)... The Rhodo in question, is a dog tooth crystal, I suppose from N'Chwaning or Uchucchacua, and, obviously in my opinion, cutting is a way to get worse, not better! Ciao Ale!

10th Jul 2009 18:01 UTCAlessio Piccioni

Ciao Simone i agree, what you say, but many times gem cutter use a broken cristals, sometime if i have a lot of piece i cut a perfect cristal.

For example the phosgenite was a single clear flat cristal, the owner of phosgenite cristal ask me cut the cristal. He give me also gem cristal baryte for cut, in this case for have a good clear gem is necessary cut good cristal.

11th Jul 2009 10:41 UTCRay Hill Expert

I try to NOT cut any really good crystals, if I can avoid it...that comes from being a long time crystal collector first and a gem collector 2nd. So I guess I will stay with those broken or chipped guys for now and suffer the potential loss of stones cut from great crystals...

but Allessio please know that this is my personal stance for ME, not meant as a criticism of your business practice as you described it...

13th Jul 2009 09:29 UTCAlessio Piccioni

No problem Ray.:)

7th Feb 2011 23:59 UTCEmma

How to take care of a rhodochrosite nacklace?

8th Feb 2011 02:17 UTCMichael Hopkins

Give it to me. I'll take care of it.

8th Feb 2011 05:24 UTCNoah Horwitz

Rhodochrosite is very soft relative to other gemstones (hardness of 3.5-4 vs. 7 for quartz, 9 for ruby/sapphire, 10 for diamond, etc.), so it is very important to protect the necklace from scratches. I would keep it wrapped in soft cloth or a jewelry or glasses case. Do not put it in a drawer with other jewelry (without wrapping/protection), as gemstones or even glass could scratch the rhodochrosite.

From the discussion above, it sounds like temperature changes could also crack the rhodochrosite. I don't know how much of an issue this would be, eg. if the necklace should be worn on a cold day, but certainly store it indoors in a heated area.

9th Feb 2011 03:35 UTCJamey Swisher

I would use John Bailey's Q Voodoo Polish as it is for quartz/sunstone, but seems to work nice on softer materials as well, or his 50K Voodoo works amazing on Fluorite so should work good on the rhodochrosite. I would try a Darkside lap or if that does not work, a Corian lap. Just keep it cool! I would use CA to dop. When polishing run that lap very very slow and barely any pressure, maybe even just the weight of the dop arm or less. I have never used it for faceting, but, for cabbing my fall back polishing method for softer stones is ZAM or M-5, both work amazingly well and will put a mirror polish on materials no other polishes can! For faceting I have also sometimes used a mixture of what 50K Voodoo was left on the Darkside, and then used the BattSticks to apply a tiny bit of CeO and AlO both, really knocked out a fluorite in seconds going right from a 600grit topper to the combo on the Darkside, again, running very slow.

10th Feb 2011 00:19 UTCAdam Kelly

Noah, from what I understand smaller pieces are not as susceptible as larger ones.

If these are small beads on a strand, shouldn't be much of a problem.

My ladyfriend has a large Argentina rhodochrosite pendant.

It's a polished cross section of a stalactite, and she wears in Colorado winters, and New Mexico Summers.

No problems so far, other than slight scratches as you said.

13th Feb 2011 16:34 UTCAnonymous User

Thanks for the information. Will a ceramic lap work in-place of a Corian one? I have been practicing with Calcite to get the feel.

18th Feb 2011 04:29 UTCJamey Swisher

I don't think a Ceramic would do the trick. I think you would more then likely end up with serious scratching. Ceramic laps are not even any good until they are nicely broken in to start with, lol! Corian laps are cheap though and are an awesome fallback for polishing almost any stone quartz or softer, especially with Voodoo Polish.

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