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Author Topic: New to Opals. Some questions  (Read 1953 times)

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Bluetangclan

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New to Opals. Some questions
« on: November 28, 2016, 06:21:27 AM »

Hello! Been cabbing for a while and got hold of some relatively cheap flame opals to add to some other opal including lightning ridge, boulder, and flame rough that I picked up in an estate sale recently and having a blast seeing what they have in them. In the past I hadn't wanted to mess with opal out of fear of screwing what little I had up, but now figured I had plenty of fire and started removing the matrix to see what I have. Funny since I got into this hobby initially after having a long random conversation with an opal carver from Cali I started talking to at Disney world. Now to the questions:
1. Obviously there is a difference between opal work and cabbing. I should be trying for a flat side and a dome but keeping the rough shape of whatever it ends up? In working with the rough flame, they are coming up with many odd 3 dimensional shapes so I am trying to figure out with to do with them in this case. For example I pulled a beautiful tiny pyramid shaped opal with awesome fire but from a cabbing and pendent, I am wondering what the heck to do with it?

2. Storage, I have some opals, believed to be lightning ridge rough I picked up in a small jar from an auction from William Holland school, they are suspended in water. Is this the proper way to store opals? I have heard they will crack and would prefer to avoid that. My fire opal rough was not stored in water, should I keep them that way after I pull the opals out? I assume the limited time they spend in water while I work them wont matter much?

3. Backing, I assume they mostly need backing unless they are really thick?(I don't think any of mine qualify) What kind of stone is popular for this? Obsidian? what kind of epoxy is best for this?(yeah I know everyone has their favorite).

4. Over the top of them, one guy I know mentioned to me to put on a thin layer of optical quartz? He is the only person I have talked to mention this, that normal?

5. Post cutting, whats a good polish? I normally use zam for cabs but am thinking that's not the way to go with opals. Any kind of stabilizer to use as well?

Thanks for reading.
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hummingbirdstones

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Re: New to Opals. Some questions
« Reply #1 on: November 28, 2016, 07:46:44 AM »

Hi there!

First off, could you please explain what you are calling flame opal or where it's from.  Not sure what opal this is -- Ethiopian or Mexican?  There really is no difference in cabbing opals from anything else you would cab.  Obviously you don't want to use your lower grit wheels on them so you don't accidentally grind off color before you realize it.  Slow and easy is the name of the game, with a lot of examining your rough before you start working it to make sure you're facing the color bars up to maximize brightness and then during the whole process of cabbing.  "Grind a little, look a lot" is the age-old adage for opal cutters.

Shapes are totally up to you.  Vince and I cut a lot of non-standard shapes with opal to retain carat weight.  However, we will cut off a blemish in a stone and make a smaller, higher quality (and higher priced) opal if the rough warrants it.  Non-standard shapes will require custom setting, but that's pretty much the way it goes with opals.

Most opal is sold in jars of water because it shows the color better.  Rough always looks better wet.  It does not need to be kept in water, however.  A certain percentage of opal will crack or craze no matter what -- it is the nature of the beast.  It's better to have it crack if it's going to before you sell it to someone.  I've worked opals that have been dry for a long time and walked away for a minute, come back to work on the opal and a crack has developed in the cab.  Cabbing (and carving) releases stress cracks in opal sometimes and you just can't do anything about it.  Sometimes you can cut the crack out or make two smaller cabs, but it's just how it goes.  Get use to the fact that it happens.  A lot depends on the depth the opal came from and how it was mined.

Solid opals are more valuable than doublets or triplets.  The only time you would need to back an opal is if the opal is too thin to set.  Sometimes you will come across a piece of rough that is very thin but has outstanding color.  You would then make a doublet or triplet out of it to make a cab that could be used in jewelry.  A doublet can either be backing and opal or opal and a quartz cap.  A triplet is both backing and cap with the opal sandwiched in the middle.  A quartz cap will magnify the pattern in the opal and a black backing on crystal opal will sometimes make the color really pop.  You assemble doublets and triplets before you cab them.  Black backing is usually used for crystal opal.  Black potch, obsidian, basenite and black jade are popular.  The most popular epoxy to use for making doublets and triplets is Epoxy 330 because it is crystal clear and does not yellow over time.  The only time you would consider making a doublet or triplet with opal is if the rough is too thin to cab by itself or the color bar is so thin that you can't risk grinding away the bar.  Making a doublet or triplet automatically reduces the value of the opal.

To polish opal you can use diamond or cerium oxide.  I have used both.  You can use diamond up to 14,000 or 50,000 grit or use diamond to 14,000 and then hit it with some CeOx to make it pop.  If you use CeOx, make sure to keep the opal moving and don't let it get too hot.  Give it a dunk in some room temperature water if it get's too warm before you continue.  You don't need to stablilize opal if it's healthy.

Hope that helps!



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Robin

Bluetangclan

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Re: New to Opals. Some questions
« Reply #2 on: November 28, 2016, 08:08:20 AM »

The guy I got it from calls it flame opal. The rough is in white and tan/brown matrix and a lot of the opal is in orange crystal as opposed to clear or white crystal(using crystal for a lack of better words to describe the clear rock the fire is in and totally assume my terminology is incorrect :) ). I am at work so I don't have any pics on hand of my stuff but looking it up on ebay makes it look like Mexican opal like this http://www.ebay.com/itm/7-30ct-Mexico-100-Natural-Raw-Rough-Fire-Opal-Matrix-Crystal-Specimen-1-45g-/122210819154?hash=item1c74551c52:g:VoUAAOSwB09YG2nB and that's pretty much like what my rough looks like.
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hummingbirdstones

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Re: New to Opals. Some questions
« Reply #3 on: November 28, 2016, 08:23:44 AM »

Ok, Mexican it is!  If the opal is big enough to cab by itself, then that is the way to go with cherry or orange Mexican opal.  If the pieces of opal are big enough and really clean, faceters like to cut it.  Larger pieces of cherry opal are pretty hard to come by now and the rough commands a decent price.  Just a thought.

If the opal pockets are small in the rough you have you can cut them with the matrix surrounding them.  They are called Cantera opal when cut in matrix.  Here's a link:  https://www.google.com/search?q=cantera+opal&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwiz4OOP7svQAhXGlVQKHUDzAFQQsAQIKA&biw=1600&bih=736
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Robin

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Re: New to Opals. Some questions
« Reply #4 on: November 28, 2016, 12:12:38 PM »

   Okay, if you want accurate help you really need pictures and include a coin or ruler for size, it is important.  You might want to consider breaking your questions into groups and let some experts pipe in on the area they know best. Lots of great help here but that is a big load for one message. Love that Cherry Opal....
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