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 8:24 am

All times are UTC - 4 hours




Post new topic Reply to topic  [ 2 posts ] 
Author Message
 Post subject: Gemological Characterization of Sapphires from Yogo Gulch
PostPosted: Tue Aug 24, 2021 1:39 pm 
Offline
Site Admin
User avatar

Joined: Sun Oct 16, 2005 12:22 pm
Posts: 21602
Location: San Francisco
Gemological Characterization of Sapphires from Yogo Gulch, Montana
Nathan D. Renfro, Aaron C. Palke, and Richard B. Berg
Gems & Gemology, Summer 2018, Vol. 54, No. 2 wrote:
ABSTRACT

Yogo Gulch in central Montana is one of the most important gem deposits in the United States. Although very little material has been recovered there in recent years, it has produced several million carats of rough sapphire over the course of its history (Voynick, 2001). These stones, known for their vibrant untreated blue color and high clarity, have always commanded a price premium, especially in sizes larger than 0.75 ct. This paper offers a thorough gemological characterization of Yogo sapphire, which may be unfamiliar to many gemologists. Fortunately, Yogo sapphires are unique and experienced gemologists can easily separate them from gem corundum of different geographic origins throughout the world, making it possible to determine the provenance of important stones from this deposit.




Top
 Profile  
Reply with quote  
 Post subject: Re: Gemological Characterization of Sapphires from Yogo Gulc
PostPosted: Wed Aug 25, 2021 5:01 am 
Offline
Gemology Online Veteran
User avatar

Joined: Wed Dec 16, 2009 5:03 am
Posts: 921
Location: Paris
Thank you Barbra . I love Montana Sapphires as well as Montana !

some Yogo Sapphires from Montana Technological University in Butte


Attachments:
IMG_20170925_134021.jpg
IMG_20170925_134021.jpg [ 90.17 KiB | Viewed 736 times ]

_________________
danielle

"I always believed in being myself"- Thelonious Monk
Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 2 posts ] 

All times are UTC - 4 hours


Who is online

Users browsing this forum: No registered users and 19 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