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 Fri Mar 29, 2024 1:34 am

All times are UTC - 4 hours




Post new topic Reply to topic  [ 11 posts ] 
Author Message
 Post subject: Estimating Weight
PostPosted: Sat Dec 15, 2012 9:30 pm 
Offline
Established Member
User avatar

Joined: Tue Dec 11, 2012 6:34 pm
Posts: 13
Location: Rome (Italy)
Hi to all,
on the forum I found an useful document on how to measure the weight in carats of a mounted stone.
There is a list of different shapes of gems, but the part I don't understand is the therm S.G.

this is an example:

Round faceted stones:
Diameter squared x depth x S.G. x .0018 = carat wt.


What does it means?
Thank you

_________________
Davide

My Channel


Top
 Profile  
Reply with quote  
 Post subject: Re: Estimating Weight
PostPosted: Sat Dec 15, 2012 10:03 pm 
Offline
Gold Member

Joined: Thu Apr 17, 2008 1:47 am
Posts: 1350
Location: Pacific Northwest
specific gravity

_________________
I just dreamed that I was a butterfly.


Top
 Profile  
Reply with quote  
 Post subject: Re: Estimating Weight
PostPosted: Sat Dec 15, 2012 11:42 pm 
Offline
Moderator
User avatar

Joined: Mon Apr 02, 2012 9:31 pm
Posts: 4015
Location: North Carolina
Specific gravity is a unitless measure of density. The SG is, however, exactly the same as the density in grams per centimeter cubed.

_________________
Rough and cut classic and exotic synthetic gems:https://store.turtleshoard.com


Top
 Profile  
Reply with quote  
 Post subject: Re: Estimating Weight
PostPosted: Sun Dec 16, 2012 11:33 am 
Offline
Established Member
User avatar

Joined: Tue Dec 11, 2012 6:34 pm
Posts: 13
Location: Rome (Italy)
Thank you. now I understand.
Here in italy we say "peso specifico" that is literally "specific weight".

That's really an useful document!

_________________
Davide

My Channel


Top
 Profile  
Reply with quote  
 Post subject: Re: Estimating Weight
PostPosted: Sun Dec 16, 2012 11:51 am 
Offline
Site Admin
User avatar

Joined: Sun Oct 16, 2005 12:22 pm
Posts: 21602
Location: San Francisco
Our Gemology Project SG Page has a handy list at the bottom of the page:
http://www.gemologyproject.com/wiki/ind ... ic_Gravity


Top
 Profile  
Reply with quote  
 Post subject: Re: Estimating Weight
PostPosted: Sun Dec 16, 2012 12:18 pm 
Offline
Established Member
User avatar

Joined: Tue Dec 11, 2012 6:34 pm
Posts: 13
Location: Rome (Italy)
Thank you Barbra.
So now I have also a list of specific gravity :wink:


But one question: for diamonds brilliant cut I have this instrument for a quick and non precise measurement.
Image

Do you think is appropriate for a quick measurement for diamonds??
And for other types of stones?

_________________
Davide

My Channel


Top
 Profile  
Reply with quote  
 Post subject: Re: Estimating Weight
PostPosted: Sun Dec 16, 2012 1:19 pm 
Offline
Site Admin
User avatar

Joined: Sun Oct 16, 2005 12:22 pm
Posts: 21602
Location: San Francisco
Quick, yes, precise, no. :D


Top
 Profile  
Reply with quote  
 Post subject: Re: Estimating Weight
PostPosted: Sun Dec 16, 2012 4:14 pm 
Offline
Gemology Online Veteran
User avatar

Joined: Sun Oct 04, 2009 11:18 am
Posts: 595
Location: Madrid, Spain
Davide, for small mounted diamonds it's much more accurate to use micrometer loupe + tables or formulas to convert measurements to carat weight.
For example this model.

_________________
http://gem-sphalerite.com
http://gems-inclusions.com


Top
 Profile  
Reply with quote  
 Post subject: Re: Estimating Weight
PostPosted: Mon Dec 17, 2012 1:13 pm 
Offline
Site Admin
User avatar

Joined: Sun Oct 16, 2005 12:22 pm
Posts: 21602
Location: San Francisco
Thanks Egor, that is the tool I use for weight estimation.


Top
 Profile  
Reply with quote  
 Post subject: Re: Estimating Weight
PostPosted: Mon Dec 17, 2012 9:18 pm 
Offline
Established Member
User avatar

Joined: Tue Dec 11, 2012 6:34 pm
Posts: 13
Location: Rome (Italy)
Really useful tool! It will be my christmas present! I have to buy it absolutely :mrgreen:

_________________
Davide

My Channel


Top
 Profile  
Reply with quote  
 Post subject: Re: Estimating Weight
PostPosted: Thu Dec 27, 2012 11:55 am 
Offline
Valued Contributor
User avatar

Joined: Tue Mar 13, 2007 11:12 am
Posts: 484
Location: Chiang Rai Thailand
GT Pro is a program you can buy that will help you estimate weights and so much more. I don't sell them but sure use mine. Best regards, Lee

_________________
http://stores.shop.ebay.com/Gemtown-USA-gemtownusa-GemtownUSA
https://www.etsy.com/shop/leesgems?ref=hdr_shop_menu


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 11 posts ] 

All times are UTC - 4 hours


Who is online

Users browsing this forum: No registered users and 10 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