Inclusions in Sapphire

[pyramid]

In black and midnight blue sapphires how would inclusions appear, would they be lighter or would they be invisible?

Also what is colour change blue sapphire, is it natural and are they in good supply or is there a shortage of them?

 

[mogok]

Hello,
if the sapphire is very dark so the inclusions will be slightly more difficult to see without a powerful light source. Bur if you are using a regular dark field or a fiber optic illumination there will be no problem as dark in tone does not means opaque... The background behind the inclusion will just be dark.

About color change sapphires you have to differenciate between many sapphire that are "color shift" which mean that they will change from blue to violet (which is the neighboring hue on the color wheel) and then the more rare color changing stones that change from typically a bluish grey green or a greenish grey blue to a purplish pink or a pinkish purple.
I've never seen any sapphire with a color change from green to red as I think only some excellent alexandrite can give.

You can see many example of color change and color schift specimens from Mogok (Burma) visiting the following link:
color shift sapphire crystal
color change sapphire crystal
color shift sapphire crystal
good color change sapphire crystal
an other good color change specimen

Finally a good color change sapphire cut stone

All the best,

 

[pyramid]

Thank you Mogok. I wondered if the inclusions would look white as they do in diamond due to the gap between the crystal in a crack but they do not of course because the stone is blue as is the background.

Very interested in the colour change sapphires as I had never heard of them before.

 

[rubydick]

Just a note in support of Vincent''s excellent post. The color in color-shift sapphires is generally produced by a combination of blue (Fe + Ti) and red (Cr) in the same stone, thus lending it a violet color.

Far more rare is the true color-change sapphire. These generally come from Mogok in Burma and are quite rare. They owe their color change to vanadium, just like the Verneuil synthetic, and show a similar absorption spectrum (single line at about 473nm, band centered at 580, fluorescent line at the end of the red).