Predicting firescope, brilliancescope, isee2 results from stone dimensions?

[Lal]

Hi there,

I have to say that this forum has really enlightened us and now we are trying to be ever so careful in purchasing a diamond.

We live in Vancouver, Canada and are exploring our options in terms of purchasing locally or over the net.

If we had all the dimensions on a diamond, how well can we use this to help predict results on brilliancescope, isee2, and firescope? It is not likely that we will have local access to these instruments so we want to determine some way to ensure that the diamond is a real performer. We understand that we can use the HCA, but it probably isn''t enough to help make a decision?

Thanks for all your input!
Lal

 

[mdx]

Hi Lal
I think you will have a bit of difficulty finding an Independent Unbiased Appraiser or Grading laboratory that could test your diamonds on a Brilliantscope or Isee2 device.

It seems that they are instruments used mostly by retailers, which is a little like a jeweler producing his own grading certificates.

The HCA is good tool to eliminate poor performers, thereafter I would suggest that you deal with a company with a good return policy and who is willing to send the diamond to a good appraiser like Dave Atlas or Richard Sherwood

Regards
Johan

 

[valeria101]

The HCA is built to be a predictor for all those, and it surely is not a bad one

. You can go the appraiser route or just get a stone with the test you most trust already performed by the seller (I guess the stones from GoodOldGold and DBOF may have them all). Also, the HCA was built with a "pair" tool- the IdealScope. While the HCA helps eliminate the "passable" by numbers, the scope can help choose top stones among what HCA selected. It may not be practical for you to choose among lots of diamonds by hand, but an Iscope (or similar) test on the stone, performed by the seller or/and by you, you buy would give a reasonable precise signature of the stone's optics...

Just a thought, of course.

 

[Rhino]

It is not my intent to be disagreeable but it is utterly impossible to be able to predict the optical outcome based on just Sarin measurements. There are a number of factors that greatly influence the outcomes on these optical exams and a *great* score on the HCA does not always correlate. We have a couple of diamonds in our "learning stones" section that gets a 1.0 and a .3 on the HCA whose outcomes do not correlate whatsoever. I can also point to various stones on our website that have identical crown angles, pavilion angles, table size, girdle and culet that have pretty drastic differences in B'scope results & Isee2 results based on minor facet cutting and variances in both the major and minor facets.




Getting the basic Sarin proportions are a good start and are at least a *minimum* in helping to determine what will be good and what isn't but there are many more details that go into determing the overall optical properties of a diamond. Changes in the lower girdle facet length alone can change the appearance of the stone drastically. You may want to review our tutorial on the minor facets. The more details you can give us on what you're looking at the better. If we can know

• the variances on the major facets...
  
• star/upper girdle ratio
  
• lower girdle facet length or depth (important)
  
• lower girdle angles
  
• upper girdle angles

Then I can give you a better idea how they would score.

Peace,

 

[Lal]

Can all of these details be found from a Sarin report or AGS certificate?

 

[mdx]

Yes Lal they are available on Sarin/Ogi reports but you would need to consult a suitably qualified person interpret the data for you.
Johan
Melbourne Diamond Exchange Ltd.