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,

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

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.

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