Color zoning in sapphires

[ger100]

Hi,

Can anyone explain to me how color zoning effects the value of a sapphire?
Also, is there one area of sapphire origin which shows more zoning?

I''ve noticed that African and Thai sapphires are commonly zoned, the latter often with yellow or green. I''ve also seen in a discussion of the 3 types of stones (for grading) that zoning doesn''t seem to matter!? Perhaps it is the DEGREE of zoning that matters? Or "eye appeal"??

This is a picture of a supposed Ceylon sapphire, with striped clear zoning. How does this zoning effect the value??

Thanks
Ger

 

[ger100]

BTW, the photo is of the BACK of the stone.

 

[strmrdr]

only zoning visible face up would have much effect on the value.
Do you have a face up view?

 

[ger100]

Sorry that WAS the front. Here is the back.

 

[ger100]

Sorry about that photo mix-up. Oh, and the stone is 2 ct., roughly 8 x 7 x 4.

 

[riogems]

Zoning under a microscope is natural. Eye visible zoning, such as the example of the photo you attached, it clearly has a large colorless area near the middle of the stone, is going to have a substantial impact on the value. Again, the rule of thumb is if it impacts the beauty of the stone, it is going to have an impact on price.

 

[ger100]

Adam,

Any rule of thumb on value loss for zoning, assuming the stone is otherwise pretty nice, well-cut, etc.? Or is it one of these "eye appeal" things, where it depends on severity, size and use of the stone, etc.?

I''d read that people prefer zoning in a real stone over a synthetic...obviously that means they want them. I just can''t place where the zoning prices fit in. I''d guess that synthetics are something like 10% of the cost of a good earth sapphire, maybe? Where does the zoning fit it?

Ger

 

[C Smith]

Anything that affects the beauty of a stone face-up will affect value. Color zoning as obvious as that in your picture will drop the price a great deal over a similarly cut and colored stone with no eye-visible zoning through the table. Unfortunately, there is no real hard and fast formula for just how much that will be. Colored gemstones are not so easily valued and quantified as diamonds. It''s worth whatever someone is willing to pay for it ultimately.

 

[riogems]

Hi Ger -

I think what you read may be some justification for selling a stone with zoning -- ie proof it is a real stone. There are plenty of stones without eye visible zoning, but visible with a loupe. Or at least without eye detracting zoning.

A synthetic should be worth way less than 10% of a good earth sapphire (I would think maybe 1-3%).