For those who like riddles

[pricescope]

What is it?

 

[tonysgeko]

Leonid, is it a cz? A white topaz? A rhinestone?

 

[pricescope]

No Tony.

I'll give you a hint: it is one and the same diamond in Brilliance Scope

 

[tonysgeko]

Leonid, is it a nailhead or fish eye diamond?

 

[pricescope]

Nope - a bit deep but not a nailhead or fisheye

 

[tonysgeko]

Leonid, an old european cut?

 

[pricescope]

no-no just ordinary round.

 

[jamesd]

Aren't you supposed to have the table side facing the light, not the pavilion?

 

[pricescope]

Hi JamesD

Ok. It was a steep/deep stone:
Total Depth: 63.3%
Pavil.Depth : 44.1%
Pavil.Ang: 41.6°
Crown.Ang: 36.0°
Table Size: 59.0%

Its Brilliancescope white light reading was Very High despite of the severe light leakage under the table (see below).

Diamond in Brilliance scope is placed under a white hemisphere reflecting light onto pavilion. Diamonds that leak light will benefit from it.

Left picture corresponds to the normal Brilliancescope measurements.

I tried to block the light entering through pavilion (more real situation when diamond is set in the ring) using small black cup. Picture in the middle shows what Brillincescope “sees” when there is no back light allowed. You can see nasty black (“dead”) area under the table. This is what you will get when such a diamond will be set.

Picture on the right is taken also with closed pavilion but instead of black cup I used yellow sticky tack.

Any comments?

 

[jamesd]

>> placed under a white hemisphere reflecting light onto pavilion

(groan)

Beyong that, maybe I should let those who think this is a good idea comment.

Does the hemisphere include light coming in from the angles which are inevitably obstructed by a finger?

 

[pricescope]

yes James...

 

[pricescope]

here is an H&A Tolkowsky ideal in BS: normal background illumination (left) and with black cup (right).

Slight difference shows minor light leakage under the table. One also can see effect of leakage through pavilion mains.

James, pavilion mains leak quite a bit of light even in ideal cut diamond.

You cannot see it in Firescope but Ideal-Scope shows it very clear.

 

[pricescope]

Oh! I've just shown how to use BS to detect light leakage!

S-M-R-T

 

[StevL]

Thanks for pointing me this way Leonid!

 

[student]

That is interesting! It would be even more interesting if you could find a pair of diamonds such that the ideal-scope revealed the first diamond to have more leakage than the second, while the B-scope gave the first a higher score.

 

[diamatuer]

Or how about a Superbcert next to an 8*? Let the inevitable comparisons begin ....