January 24 Through February 4—TUCSON, ARIZONA: Annual show
Welcome to the GemologyOnline.com Forum
A non-profit Forum for the exchange of gemological ideas
It is currently Thu Mar 28, 2024 6:46 am

All times are UTC - 4 hours




Post new topic Reply to topic  [ 20 posts ]  Go to page 1, 2  Next
Author Message
 Post subject: Jasper vs Sugilite
PostPosted: Sat Feb 09, 2013 1:01 pm 
Offline
Established Member

Joined: Fri Jul 24, 2009 10:36 pm
Posts: 29
I am having trouble trying to differentiate sugilite jasper (dyed jasper) from real sugilite, as photoed in the two pictures below.

What are some of the distinct features to tell the two apart?
Thanks.


Attachments:
File comment: Japser
jasper.jpg
jasper.jpg [ 39.38 KiB | Viewed 5270 times ]
File comment: Sugilite
sugilite.jpg
sugilite.jpg [ 57.32 KiB | Viewed 5270 times ]
Top
 Profile  
Reply with quote  
 Post subject: Re: Jasper vs Sugilite
PostPosted: Sat Feb 09, 2013 11:57 pm 
Offline
Site Admin
User avatar

Joined: Sun Oct 16, 2005 12:22 pm
Posts: 21602
Location: San Francisco
The Refractive index of sugilite is 1.607-1.610.

The refractive index of jasper is 1.540 (+/-).


Top
 Profile  
Reply with quote  
 Post subject: Re: Jasper vs Sugilite
PostPosted: Sun Feb 10, 2013 4:02 am 
Offline
Platinum Member
User avatar

Joined: Fri Feb 24, 2006 1:20 am
Posts: 2756
Location: Southern California, U.S.A.
After having cut quite a bit of sugilite I think the beads shown are dyed ...jasper or whatever. But there's a potential problem of using RI to segregate sugilite from quartz.

From G & G, Summer 1987: "The research reported here revealed that there are actually two types of gem materials that have heretofore been called sugilite: one that is predominantly manganoan sugilite with minor impurity minerals, and the other that is chalcedony mixed with (and colored by) sugilite."

I've never seen the natural sugilite-hued "gem silica," but it's something to keep in mind.

_________________
Rick Martin

www.artcutgems.com


Top
 Profile  
Reply with quote  
 Post subject: Re: Jasper vs Sugilite
PostPosted: Sun Feb 10, 2013 6:30 am 
Offline
Gold Member

Joined: Wed Jan 23, 2013 5:29 pm
Posts: 1047
Location: Paris
I don't know if that can help, for visual identification, but in the case of jasper dyed blue to imitate lapis lazuli, very often you can see "islands" of transparent, monocristalline quartz where the dye doesn't penetrate.

Maybe it's the same for purple-dyed jasper.


Top
 Profile  
Reply with quote  
 Post subject: Re: Jasper vs Sugilite
PostPosted: Sun Feb 10, 2013 12:14 pm 
Offline
Site Admin
User avatar

Joined: Sun Oct 16, 2005 12:22 pm
Posts: 21602
Location: San Francisco
So, Isi, you don't own any gemological testing tools?
Perhaps one can visually determine if something is dyed, but that won't identify the material.

Have you tried rubbing a bead in an acetone soaked cloth?


Top
 Profile  
Reply with quote  
 Post subject: Re: Jasper vs Sugilite
PostPosted: Sun Feb 10, 2013 4:55 pm 
Offline
Gold Member

Joined: Wed Jan 23, 2013 5:29 pm
Posts: 1047
Location: Paris
Of course I prefer to use gemological tools when I can : nothing better than a good RI in spot lecture, not to speak of SG which is as well different for jasper and sugilite.

But when you are on a show or in a shop and with nothing but your loupe in the pocket, it's good to be able to rely on some observations about how the dyeing products usually behave !

Some days ago a friend bought a green dyed quartz necklace for the price and in the name of jadeite. With a bit of better observation he would have been able to determine, when still in the shop, not the name of the mineral, but at least that the repartition of color was suspect to say the least !


Top
 Profile  
Reply with quote  
 Post subject: Re: Jasper vs Sugilite
PostPosted: Sun Feb 10, 2013 6:24 pm 
Offline
Site Admin
User avatar

Joined: Sun Oct 16, 2005 12:22 pm
Posts: 21602
Location: San Francisco
If I purchased gems under conditions where vendors routinely engaged in fraudulent misrepresentation which was not legally actionable, I would carry instruments.
Actually, I would buy elsewhere.


Top
 Profile  
Reply with quote  
 Post subject: Re: Jasper vs Sugilite
PostPosted: Mon Feb 11, 2013 5:38 am 
Offline
Gold Member

Joined: Wed Jan 23, 2013 5:29 pm
Posts: 1047
Location: Paris
Yeah, well, so would I.

Especially if, like was the case for my friend, the "jade" necklace was supposed to be a birthday present for an Asian lady who, when she saw the "thing", nearly flew it at his face !... :shock:


Top
 Profile  
Reply with quote  
 Post subject: Re: Jasper vs Sugilite
PostPosted: Mon Feb 11, 2013 9:23 am 
Offline
Established Member

Joined: Fri Jul 24, 2009 10:36 pm
Posts: 29
Thanks for your reply. In terms of price, is there a big difference between sugilite and jasper? Is sugilite an expensive gemstone?


Top
 Profile  
Reply with quote  
 Post subject: Re: Jasper vs Sugilite
PostPosted: Mon Feb 11, 2013 1:01 pm 
Offline
Established Member

Joined: Thu May 20, 2010 2:21 am
Posts: 32
Location: Chicago, Illinois
There is a huge difference in terms of price. Sugilite can be about as expensive as opaque gemstones get. Even the finest jaspers would be a fraction of the price.

I don't have a ton of experience with sugilite, but here is my pseudo-informed opinion: Those beads look like dyed something-or-other to me. Sugilite has more purple tones (your beads look fairly pinkish on my monitor). Also, there is the absence of any of the blue or brown minerals (richterite and I forget what the brown is) that typically are found in all but the finest pieces of sugilite. Further, I don't recall white matrix/inclusions being commonly associated with sugilite at all.

Sugilite is pretty hard, if I recall, somewhere above a 7 so if it scratches easily with a knife or quartz point then you can be sure it is not sugilite.


Top
 Profile  
Reply with quote  
 Post subject: Re: Jasper vs Sugilite
PostPosted: Mon Feb 11, 2013 1:37 pm 
Offline
Platinum Member
User avatar

Joined: Fri Feb 24, 2006 1:20 am
Posts: 2756
Location: Southern California, U.S.A.
fzpanda, the value depends on the quality as with any gemstone. I've heard of $200/ct. prices for the finest translucent gel sugilite while many of the lower-end opaque stones sell for much less. Still they are usually priced higher than most jaspers.

I think the simplest test you can apply is to consider the price of the bead strand in question. There's a huge amount of labor involved in shaping, polishing and drilling beads like that. Based on the price for rough sugilite of that color I'd guess that if your strand is priced at less than $500 or so you should be very skeptical.

A quick internet search just now revealed similar-looking "sugilite" strands being sold for under $20. That doesn't pass my smell test.

_________________
Rick Martin

www.artcutgems.com


Top
 Profile  
Reply with quote  
 Post subject: Re: Jasper vs Sugilite
PostPosted: Mon Feb 11, 2013 5:52 pm 
Offline
Valued Contributor
User avatar

Joined: Thu Oct 04, 2012 1:57 am
Posts: 138
Location: Germany
I agree thet these beads look like dyed somthing, not like Sugilite at all.
I am not an expert in Sugilite but I use mid-quality stones (Sugilite in Matrix) in my silver jewellery.

Quote:
Also, there is the absence of any of the blue or brown minerals (richterite and I forget what the brown is) that typically are found in all but the finest pieces of sugilite.


I disagree on this - Richterite may or may not be present. Most of the time it is not, I'd say..

I think it's less hard - 6 to 6.5 according to Walter Schumann.
I see white and brown parts in the matrix.

Some of my pieces, this is rather commercial grade material...


Attachments:
sugilite_web.jpg
sugilite_web.jpg [ 137.17 KiB | Viewed 5149 times ]


Last edited by Michael P. on Tue Feb 12, 2013 12:54 am, edited 1 time in total.
Top
 Profile  
Reply with quote  
 Post subject: Re: Jasper vs Sugilite
PostPosted: Mon Feb 11, 2013 11:53 pm 
Offline
Platinum Member
User avatar

Joined: Fri Feb 24, 2006 1:20 am
Posts: 2756
Location: Southern California, U.S.A.
Here are some other examples of medium grade sugilite cabs, showing color variations one can expect. I have some very nice top color gel but it's not yet cut.
Attachment:
DCab 63e.jpg
DCab 63e.jpg [ 167.03 KiB | Viewed 5136 times ]

Attachment:
DCab 65e.jpg
DCab 65e.jpg [ 146.13 KiB | Viewed 5136 times ]

Attachment:
DCab 54e.jpg
DCab 54e.jpg [ 129.29 KiB | Viewed 5136 times ]

_________________
Rick Martin

www.artcutgems.com


Top
 Profile  
Reply with quote  
 Post subject: Re: Jasper vs Sugilite
PostPosted: Tue Feb 12, 2013 12:36 am 
Offline
Established Member

Joined: Fri Jul 24, 2009 10:36 pm
Posts: 29
Thank you all for the valuable info. My fascination with pink sugilite originated from the sugilite cab shown in the pictures below. This type of pinkish-white patterned sugilite is extremely popular in the Asian markets right now, and is given the beautiful name of "sakura sugilite". They often command a higher price than their purple counterparts.

I was very impressed by the beautiful color of this type of pink sugilite until I found out that its color could be caused by artificial treatments.


The cab shown measures about 54*54*8mm, and weights about 39 grams. Its vivid-pink color is gorgeous, definitely different from most of the sugilites I have seen, which are purplish. The seller insisted that this cab is completely untreated. There are some yellow/brown matrix on the surface of the stone as you can see in the pictures. and the seller said the white streaks on the cab are quartz. What do you guys think? Dyed or natural? Does 100% natural "sakura sugilite" really exist?


Attachments:
sug3.JPG
sug3.JPG [ 46.42 KiB | Viewed 5131 times ]
sug2.JPG
sug2.JPG [ 28.78 KiB | Viewed 5131 times ]
sug1.JPG
sug1.JPG [ 52.46 KiB | Viewed 5131 times ]


Last edited by fzpanda on Tue Feb 12, 2013 12:53 am, edited 6 times in total.
Top
 Profile  
Reply with quote  
 Post subject: Re: Jasper vs Sugilite
PostPosted: Tue Feb 12, 2013 12:38 am 
Offline
Established Member

Joined: Fri Jul 24, 2009 10:36 pm
Posts: 29
One more pic of the same cab


Attachments:
sug4.JPG
sug4.JPG [ 45.75 KiB | Viewed 5130 times ]
Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 20 posts ]  Go to page 1, 2  Next

All times are UTC - 4 hours


Who is online

Users browsing this forum: No registered users and 15 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group
Gemology Style ported to phpBB3 by Christian Bullock