EGL Cut info for HCA rating

[micromonkey]

Hey All-I have been lurking on this site for about a week and this place is great!!!

My head is spinning and I''m on the hunt for a great diamond--I have read all the awesome turorials, info etc. and have been using the HCA to rate some physically unseen diamonds.

Some of the HQ vendors include all the angles, bscope and good stuff but others will only provide certs. I have been going through some EGL certed diamonds and using their info which only has %''s for crown/pavillion. Culet I experiemented with a .1-.5 for none--actually I went up to 1.0 and it didn''t make a difference really.

My question is how good is the EGL info to be used for the HCA? I have found a few "steals" which score pretty well and reasonably priced.

Any insight would be appreciated.

Thanks

 

[micromonkey]

Here is the stats on one I am looking at:
Depth 57.6%
Table 59%
Crown 12.2%
Pavil 43.1%

Girdle Thin to Med faceted
Culet: None

Depending on what I assume they mean for "none" on Culet I get between a 1.5 - 2.x on the HCA.

 

[Garry H (Cut Nut)]

It sounds pretty safe, but you should request the angles from the vendor.
The culet makes a difference in the abgle when you enter pav depth % because we use trig to estimate the pav angle. Culet mesurements are usually understated.

 

[Richard Sherwood]

The EGL percentages are definitely better than nothing (which is what you get from a GIA report) in determining cut quality.

They will help you eliminate poor performers, and put you in the right "ballpark". After you reach that point, you can hone in on your research to arrive at "homebase".

The problem is that the HCA is estimating the crown/pavilion angles using the crown/pavilion height/depth as points of reference. Since these percentages are rounded, then sometimes the angle derived by the HCA will be a little off from what it actually is.

Often this doesn't make a huge difference, but sometimes it does. My advice would be to hone in on your likely "candidate", and then have it run through a Sarin machine for a final anaysis.

As you state, there's always the possibility of picking up a bargain in the EGL cert world, you know what you're doing. Another big thing to watch for is that the grading is not off one color or clarity grade. If something seems like a real "steal" to you, hypothetically theorize that it might be one color or clarity grade (or both) less, and see if it still falls in the steal/deal category.

If so, you might be on the right track, and of course you can't lose if you make the sale contingent upon the diamond appraising out to your satisfaction with an independent appraiser. This is a reasonable request, which most dealers will go along with.

 

[micromonkey]

Yeah the main problem is the color/clarity for EGL. The vendor told me pretty much that---it was an SI1 and F color which if to be safe I say may be SI2 and G then the price is still good but not great.

I think I am going to just pay the higher rate and limit my choices to one's with GIA/AGS and with more detailed (ie--at least megascope) stats. I have now been looking at some by Nice Ice and Superbcert and you get so much detail you can't go wrong.

It doesn't seem like the prices are really that much higher when you figure you get Bscope or simulated results and can enter acurate info for HCA. It's hard to tell with some vendors "Best" or "very good" cut since on some that were EGL/AGS (even AGS-0) I ran the numbers and some turned out 3.6-4.8 range. I mean if you are going to spend at least $3000 there is no reason not to spend $3500 and get one you "know" is cut awesome.

I found this superbcert that I am Jonesin' for:
Diameter 6.22 (6.2-6.24) .8%
Depth: 60.8 3.78mm
crown angle 34.1 (33.8-34.4) 0
crown height 14.8 (14.6-15.1)
pavil angle 40.9 (40.8-41)
pavil depth 43.1 (42.7-43.3) 0
culet .6%
table size 55.2 (54.9-55.4)
girdle thickness 1.2% (1-1.4) Thin

HCA comes in at 1.1 and
The Bscope verifies that
White Light: Middle of V High
Color Light: TOp of V High
Scintillation: Top of HIgh and bottom of V High.

.87 VS2 / H (Gia). I can live with "H" I've seen it and it looks white to me (and her ) stones with --"I" and "J" I can tell (only a little--with other stones next to it).

In any case this forum rocks (ha ha) and I would have spend more for a worse stone at the jeweler if I hadn't stopped here.

Keep up the good work and hopefully in the future detailed cut info is put on all certs---everyone can argue about rating systems later! I know I'm preaching to the choir but it'd seem reasonable to have more detail in cut and bscope data--the cut ratings seem rather Victorian in this modern age. With the synthetic whites around the corner these labs should be doing some more detailed testing.

 

[highendgems]

the dealer you are talking to does not what what he/she is talking about. most important thing about EGL is--was it EGL or EGL USA. if it was EGL USA, buy with confidence. if EGL overseas, then the grading will likley be off on color/clarity.

EGL USA lists BOTH angles and percentages on their reports and they are highly detailed.

an EGL USA cert. is a great way to get a steal on a terrific stone.

 

[aljdewey]

I'm officially going to make this my mission: to reply to every erroneous comment made by Highendgems that I can find to hopefully stem incorrect information.

Highend expects us to believe that folks like the vendors (or like Rich Sherwood - with a gazillion and a half! years in the business)....ALL of these knowledgable people are wrong and that EGL US is the best thing since the wheel. He shares NO basis for his expertise....we're just supposed to take his word for it.

Sorry.....not buying. Some EGL US gradings are on the money. Some ARE NOT. It really doesn't matter as long as the price a customer pays reflects what the stone IS, not what the report says.

Regarding accuracy....EGL reports only give percentages on crown and pavilion. I've yet to see otherwise, so *show me*. Percentages simply ARE NOT as accurate as angles. Period. Percentages are rounded. That's like saying $1.51 and $2.00 are the same thing....when one is nearly 25% more.

Micro, you're on the right track! Keep with it.