Gemstone "secondary" colors

[luvthemstrawberries]

I have been eyeing some sapphires online and wanted to see if you colored stone experts out there could explain to me what "secondary" colors are. Most of these are blue sapphires. One says it has "teal secondaries," and one has "green secondaries." I''m curious if that just means the secondary color shows up in certain lighting, or is it always present? The one with green secondaries is ovbiously 2 different colors in its picture - it almost looks like a pinwheel with 2 very different shades in quarters of the stone. Do secondaries affect the performance of the stone? What are reasons it would be undesired?

 

[Harriet]

Date: 9/6/2008 6:23:36 PM
Author:luvthemstrawberries
I have been eyeing some sapphires online and wanted to see if you colored stone experts out there could explain to me what ''secondary'' colors are. Most of these are blue sapphires. One says it has ''teal secondaries,'' and one has ''green secondaries.'' I''m curious if that just means the secondary color shows up in certain lighting, or is it always present? The one with green secondaries is ovbiously 2 different colors in its picture - it almost looks like a pinwheel with 2 very different shades in quarters of the stone. Do secondaries affect the performance of the stone? What are reasons it would be undesired?

Take a tsavorite for example. It''s green, right? In some lighting or at some angles, it can look like it has some yellow or blue. That yellow or blue is the secondary. I''m not sure what you mean by "performance." If you mean dispersion and refraction (i.e. sparkle), secondaries have no effect, or so I think. Some people prize pure hues (no secondaries), some people prize certain secondaries (in the case of tsavorites, I prefer blue to yellow).

 

[Pandora II]

Another example is rubies - they can have a purple secondary or and orange secondary. The purple leaning stones are more prized on the whole. Personally I like the warmer orange leaning tones.

Yellow in a tsavorite is to be avoided and you will pay a premium for a blue under-tone.

Brown is a colour that is ''undesirable'' as a secondary for a lot of people - for me it''s not a definite no no.

 

[Harriet]

Plus grey in blue and purple stones.

 

[chrono]

In sapphires. most tend to avoid teal and green secondaries unless he/she happens to like it. The secondary colour does not affect the brilliance of the stone.

 

[luvthemstrawberries]

This is one of the sapphires - website says it has teal secondaries.

 

[luvthemstrawberries]

This is the teal sapphire with green secondaries - this one seems much more obvious to me.

 

[luvthemstrawberries]

I guess what I''m mainly asking is what these stones with secondary colors actually look like in person. The second picture I posted - is it going to look like 2 chunks of it are just a totally different lighter color all the way through the stone from the top down to the belly? Do secondary colors just look like different color was injected into certain parts of the stone, or does it generally mean there is an overall tone change to that entire stone?

Thanks for the help so far!

 

[ma re]

What you mean is, does secondary mean bicolor, right? Well, I think you should ask the seller that question, cause diferent sellers have diferent ways of describing stones. In my opinion secondary should mean that, for example, a blue sapphire has a greenish tint throughout. Now, an ideal sapphire has no obvious secondary hues, but those with slight purple secondary are much more prized than the ones with green. I think you should just see it in person to really be able to decide if you like it.

 

[Richard M.]

Date: 9/6/2008 11:46:06 PM
Author: luvthemstrawberries
I guess what I''m mainly asking is what these stones with secondary colors actually look like in person. The second picture I posted - is it going to look like 2 chunks of it are just a totally different lighter color all the way through the stone from the top down to the belly? Do secondary colors just look like different color was injected into certain parts of the stone, or does it generally mean there is an overall tone change to that entire stone?

There are several definitions of "secondary color" but I think you need the one that applies to corundum (sapphire and ruby). What you''re seeing in the last image you posted are strong dichroic colors. Some might refer to it as "cross color" or "secondary color."

When light enters some gem crystals it travels in 2 different directions. The color seen in those 2 directions can be very different due to selective absorption of some spectral hues. All sapphires are dichroic but the strength varies. It''s especially strong in stones from Australia and certain other locations like Songea in Tanzania. Those stones must be carefully cut with the "best" color showing through the table. Sometimes the "secondary" or "cross color" is so strong you end up with a stone that shows both colors simultaneously face-up, like the one you posted. My guess is that the image shows the stone as it really appears. Some people find the effect very pleasing.

There are quite a few other strongly dichroic gems. Tourmaline can exhibit very strong dichroism.

Richard M.