opal types???

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OpalSpectrum
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Re: opal types???

Post by OpalSpectrum »

the term - ''jelly opal'' is used for specific type of 'crystal' opal from Lightning Ridge
- it is yellowish crystal opal - it can be transparent or more cloudy semi-transparent - in most cases opals with POC have violet/blue fire - sometimes red but very dull - also this type if quite unstable and craze that is why jelly opal doesn't have big value
*this is not scientific term and some people use it to describe other types of opal

- ''crystal opal'' is term used to describe different types of transparent and semi-transparent opals vs opaque
*it can be used for any transparent opal - Ethiopia Australia Nevada Mexico etc
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Shea_O
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Re: opal types???

Post by Shea_O »

Iskandarman wrote:What is fire opal really are?
Yellow to red color?? How about with brown and brownish orange or brownish yellow??

What is the different between chrysopal and prase opal??

What is jelly opal really are??


Fire opal - has orange body tone

Honey opal/kalimaya teh or “tea opal” - has an overall yellow bodytone with a tendency towards either a slight red shade or slight brown shade. I think there needs to be further distinction amongst this type of opal. I think there should be a distinction between:
Red Honey or Red Tea and the more common yellow-brown opal which I think should be called Brown Honey or Brown Tea opal.

Red honey/tea opal or “kalimaya teh” (when of very good quality) has an awesome look similar to a fire opal but is distinctly different. It makes red POC look excellent

Cherry opal - is similar to fire opal but has none of the yellow in it, so instead of orange you have red opal. There are varying intensities of red but it is usually an almost crimson red. Play of color is very unusual in this kind of opal, but that may be because this kind of opal is already hard to find

Orange bodytone = fire opal
Yellow bodytone = honey opal or tea opal
Red bodytone = cherry opal
in between shades of yellow with brown or red tone = honey or tea opal but I think they should be called “red honey/tea opal” or “brown honey/tea opal”
Brown opaque opal = chocolate opal
Brown crystal opal = coffee opal (an Indo term; the ‘Yanks don’t have one yet)


The term “jelly opal” seems to be often used interchangeably with the term “crystal opal” but I am not so sure that they are the same. My understanding is that “crystal opal” is a term used loosely when describing the transparency of an opal. So opals that are transparent are often referred to as a crystal opal and can still have pigment of any color despite the degree of transparency.

The problem with using the two terms interchangeably comes when you see a transparent opal formed in a sedementary process (like how Australian opals are formed) where often the play of color is in streaks through the opal and there are “dead spots” whithout play of color - versus a crystal opal formed in a volcanic replacement process (like the wood opal replacements of Nevada or Banten).

From my understanding the sedimentary opal with intermittent POC is often what is being referred to when people say “jelly opal”. This often forms as knobbies. Because this opal is transparent it can end up being called a crystal opal by some people.

I think there should be a distinction between the two because there are many transparent opals without any bodytone that are formed in a volcanic replacement process, like the wood opal replacements in Nevada or Banten. These kinds of transparent opals often have POC throughout the stone and usually displays more variable POC patterns and not so much of the streaks. This is your typical crystal opal.

Is crystal opal different from jelly opal? Ironically the answer is both Yes and No because of the way we use the words.

They are both transparent (crystal-like nature) but I think there is enough difference in the way the opals were formed, and the resulting differences we see in the kinds of POC and formations (fossil replacements vs knobbies) for there to be justification for a distinction.

I am also open to being corrected if my understanding is wrong.
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SwordfishMining
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Re: opal types???

Post by SwordfishMining »

I'd have to agree that the term Jelly seemed to be used for the opals one step above potch in any play of color or the honey opal that was staying together but generally used as"driveway gravel as it was usually only purple or blue and gem cutters would not pay for the time to pick it out. When it was gemmier and not cracky over time it seems to then be called crystal. The volcanic opals always like to call themselves crystals because the brilliancy of the color from a water clear gem. Opal is the hardest gem to describe after if gets graded by being described.
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Iskandarman
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Joined: Mon Jan 11, 2016 12:34 pm

Re: opal types???

Post by Iskandarman »

Thanks. It help me to organized opals. I like banten opal from my friend mine pits because they entirely non-hydrophane type and quite stable in dry hot air. The pictures i post is my favorite piece. :)
Attachments
Tea color
Tea color
Blue red flash
Blue red flash
20.2 carats Tea opal from Banten,  Indonesia
20.2 carats Tea opal from Banten, Indonesia
Artfldgr
Posts: 399
Joined: Mon Jun 08, 2015 1:46 pm

Re: opal types???

Post by Artfldgr »

I have been to Banten before the rush on opals there... was even in a small hole mine... was a very hard trip, and not easy dealing

the funny part is a few years back, seemed no one cared for a "jelly"...

here is a lightning ridge opal... i am guessing its a jelly..
in plain light, there is almost no fire... it looks like a clear slightly yellow stone
but let some sun in, or bright light..

and
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Iskandarman
Posts: 78
Joined: Mon Jan 11, 2016 12:34 pm

Re: opal types???

Post by Iskandarman »

I guess you have several or lots of banten as well.

Ligthning Ridge jelly opal looks very beautiful when cut properly and perhaps if transparent enough could be faceted as well.
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