November 23-24—WEST PALM BEACH, FLORIDA: Show and sale; Gem and Mineral Society of the Palm Beaches; Sat. 9-6, Sun. 10-5; Adults/Seniors one day $10, two days $15, Children under 12 are free; The 57th annual Gem, Mineral, Bead, Jewelry and Fossil Show.
Welcome to the GemologyOnline.com Forum
A non-profit Forum for the exchange of gemological ideas
It is currently Thu Nov 14, 2024 6:00 pm

All times are UTC - 4 hours




Post new topic Reply to topic  [ 4 posts ] 
Author Message
 Post subject: Orienting Parti Colored Sapphire
PostPosted: Sat Mar 11, 2023 9:26 pm 
Offline
Valued Contributor

Joined: Tue Mar 27, 2012 10:15 am
Posts: 354
Location: Cary, NC
To all,

Any suggestions/wisdom on how to orient parti colored sapphire? I have some good 10 carat pieces with a great (or bad if you think that way), mix of colors and In great shapes to cur rounds, cushions, or others. My concern (not having cut much multi-colored stones), is how do you keep the colors separate (and the flash), vs just winding up with a muddied mess of every color mixing in the pavilion? In addition, is there a better cut over another to prevent the mixing. E.g. A cushion would definitely give a way to separate color zones, but it might just wind up looking like an ametrine or bi-color tourmaline design (however, the parti sapphire has more than two colors in it).

Looking for any advice, even if it's just "you roll the dice and hope it looks nice".

My thanks

_________________
Bob Hodges

Faceter: When turned into a zombie, they stumble around crying "roooouuuuggghhhh"


Top
 Profile  
Reply with quote  
 Post subject: Re: Orienting Parti Colored Sapphire
PostPosted: Sat Mar 11, 2023 10:50 pm 
Offline
Gold Member

Joined: Thu May 12, 2016 2:18 am
Posts: 1569
Bob,

Any sort of brilliant cut tends to mix the colors and muddle them. I find it best to do step cut designs, in simple shapes to maximize the separation of colors and give a sharp delinaiation between areas of color. Obviously Emerald cuts with steep ends work best for this.

Steve


Top
 Profile  
Reply with quote  
 Post subject: Re: Orienting Parti Colored Sapphire
PostPosted: Sun Mar 12, 2023 9:59 pm 
Offline
Moderator
User avatar

Joined: Fri Jun 25, 2010 10:06 pm
Posts: 2268
Location: Chapel Hill, NC / Toronto, ON
Hey Bob! There are a bunch of different things you can do, to try and get the specific effects you want.

First off, if you want to keep the colours as separate as possible, then you need to use a keeled design, and the keel needs to run perpendicular to the "splitting plane", the line that separates the two colour zones. BUT! Your outline doesn't have to be a rectangle - you can put a keeled design on pretty much any outline - a round, an oval, an oval that's rotated 90*, a triangle, etc. It doesn't need to be a step cut - I've done many bicolours using a keel that has facets on the 96 +/- 1, +/- 2, or even +/- 3, and there's been minimal mixing (maybe a slight band right in the middle of mixed colour).

If you want to mix the colours, then you have a few options. You can use a brilliant pavilion, with the dop placed directly on the splitting plane (meaning that the left half of the stone is blue and the right half is yellow). If you do this, you'll get fairly even mixing. You can do a regular brilliant pavilion, a barion, or something similar.

For more complicated special effects, you'll need to target where you place the splitting plane. If you place it parallel to the table, with the blue colour in the bottom 1/3 to 1/4 of the stone and the yellow in the table, then you'll get a so-called "halo" effect. The area directly under the table will be blue-green, you'll have a circle around that of a bit more greenish colour, and then the area closest to the girdle will be a pure yellow. You can see a great example in Phil Lagas-Rivera's work with blue flame-fusion sapphire here: https://imgur.com/a/dh8crsi.

If you want even more complicated effects, you'll need to have the splitting plane tilted and off-center.


Top
 Profile  
Reply with quote  
 Post subject: Re: Orienting Parti Colored Sapphire
PostPosted: Wed Mar 15, 2023 11:02 pm 
Offline
Valued Contributor

Joined: Tue Mar 27, 2012 10:15 am
Posts: 354
Location: Cary, NC
Steve, Arya,

Thank you both so much. Luckily, I have at least 3 pieces so I can try one cut on each and then decides what would look best for the final stone.

As always, love this place and how willing you all are in helping :).

I'll make sure to post the results in the 'off the dop' and let you two know when they get there :)

_________________
Bob Hodges

Faceter: When turned into a zombie, they stumble around crying "roooouuuuggghhhh"


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 4 posts ] 

All times are UTC - 4 hours


Who is online

Users browsing this forum: No registered users and 8 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