Buying with Gem Adviser

Open Gem Adviser .gem files by clicking on a file on RapNet or an email from a vendor. If you do not already have the 5mb free program, then please download here.

When you open the file you will immediately see a small window like the one below with the actual diamond displayed in the lighting format chosen by the vendor who sent you the file.


You can also n Gem Adviser, by clocking on start > programs or putting the little blue gem Adviser icon on your tool bar or desk top and


then using the folder file on the top left you can open and view files saved on your hard drive.

You can open and compare several stones at once:


Cut Quality:

Cut Quality is not a “Grade” per se; but it gives you additional information that is not on any grading reports.

The q---qualitytab opens the Cut Quality screen. When you open Gem Adviser it begins calculating the diamonds light performance factors on your own computer. Because the calculations are done on the fly on your computer the output information cannot be tampered with. The main Cut Quality window (center below) has three additional windows. A Tolkowsky round brilliant cut with perfect symmetry scores 1.00 for all values.


Mono shows the basic light performance for a single or one eyed view – the basis of many digital grading techniques. Stereo indicates the response you would expect to see with two eyes. Tilting to 30° is the average (weighted to face up) as the stone is rocked.

A bad dark zone score can mean part of the stone will have eye visible dull areas.

General Information:

The next tab across to the right shows the individual stone information which will be taken from the original scan of the stone. This information will vary based on the format supplied by the type of scanner; the most detailed come from OctoNus’s Helium scanners.


The Viewer Window

It is possible to rotate the stone from front to back and on different angles by dragging it with your mouse:

You can view the diamond in different lighting situations with the little globe icon:

Disco Lighting


Office Lighting

Or gemological lighting

ASET Scope


Ideal Scope

If you use the dark or black background you can see any negative dark zone effects from leakage.It is also possible to save this file as a photograph which can be emailed to clients, saved on your computer or used on your web site:


Another very powerful tool is the movie maker which in about 20 seconds makes a movie on your own computer screen (the green arrow on the top right). This will give a movie of the stone rocking from side to side. This movie can be used in your shop window or if you buy DiamCalc it can be saved, compressed into smaller files and used for many purposes such as email to customers or post the movies on your website, YouTube etc.

Here’s how to see a diamond with bad symmetry:

Bad symmetry

Bad symmetry

Diamond showing bad leakage:

Bad leakage

Bad leakage

Below is an example of a stone that was laser inscribed Hearts & Arrows, but we can see the hearts are not very good.

Heart and arrows

Heart and arrows

Video Using GemAdviser