Asscher measurement question

[Asschman]

In the course of looking (online) at several different asscher diamonds, I have been struck by the discrepancy in length x width x depth measurements. For example, two 1.01 carat stones with roughly 71 depth and 66 table percentages but one has a depth of 3.82 and the other has a depth of 3.97.

That doesn''t appear to be a trivial difference in depth, and I wonder how that affects the diamond''s appearance. Any thoughts on how this difference could be explained, and whether it is better to side with a deeper depth than a shallower one?

Asschman

 

[Asschman]

Uh anyone? anyone? Bueller?

 

[valeria101]

Well, "too deep" might mean two things (either or both):

#1. the stone looks relatively small for it's weight

#2. there is a dark patch under the table because the pavilion angles get too deep and let light out.

The more common problem is the first, and total depth may not count as much there comared to where exactly that extra depth is distributed: the wider the thich section, the more material it takes up. Basically, a thick girdle would eat up times more material than a slightly deep pavilion. Same goes for steel & deep upper and lower girdle "steps" on an emerald cut like yours.

All in all, to see if that depth has relevant impact on size is much easier to compare sizes directly (average diameter or surface) instead of comparing depths %. About half a milimyeter diameter makes a "sizeable" difference, IMO. About 0.2 would be visible side-by-side but perhaps not much once the stones are set.

Problem #2 may happen as well, but before hitting 80% depth or so, it doesn't seam likely - as far as I know. Those stones would be discounted for how small they look relative to their size to begin with. The same undesirable optical effect may occur due to less than optimal cutting, even if the extra depth is not there at all... and that's one reason why I like that Ideal Scope toy so much.


Hope some of this helps

Now, I am not saying to do this

... but my "asscher by numbers"

recipe would mean looking for a stone with 50%-55% table (I would be amazed not to get a high pavilion and the classic look with that) and depth anywhere below 75% and ideally not more than a medium girdle. I know those stones are not the biggest, but some of the extra weight makes a high crown that shows nicely from any conceivable angle fot straight down and feals "substantial" when set. Lots of fire is one more bonus on such stones.
Deep pavilions do not show in setting - so any weight there is just good to produce brilliance - not allot of depth is needed for that.

 

[windowshopper]

girdle and perhaps steepness of angles.............i would almost always go with the shallower one in an instance where the general proportions etc are right. too deep and a thicker girdle (check the asrin measurements on the gridles) i think they get flat...

 

[Asschman]

Appreciate both of your comments. Ana, I share your desire for a smaller table (56-62 or so), but these stones turned up because they feature the extra faceting that most generic asschers do not have. So I am trying to determine whether the trade-off of the extra faceting is worth the larger table size. I believe I have located another stone with percentages in line with what I would like, so I might call it in to compare against the stones with the extra facets.

Asschman

 

[valeria101]

Date: 2/8/2005 10:1:50 AM
Author: Asschman

I am trying to determine whether the trade-off of the extra faceting is worth the larger table size

Glad you brought this up.... I don''t think it is a "trade off" - the extra steps compensate somewhat for the "flat" look that a large table would produce. Besides, 60-ish is not that big.

The most visible difference that extras cannot compensate would probaly (but not necasarily) be some loss of dispersion and (surely) the prominent crown showing in mounting.

If brilliance is good and those "steps" show I woudln''t necesarily cry for the old cut recipe. New ones are nice too

Just IMO, as usual.

 

[strmrdr]

hmm how did I miss this thread.
I dont have much time because iv got to get to work but there are several other threads on it.
One of them is easy to find in the faq section.
Not to rehash what iv already said dozens of times but there is a reason asschers are going to be deep if they are properly cut.

First high crown needed for fire:
10%-15%+
Then the typical thick girdle adds another few percent.
Its real common that 17%+ is used before you get to the vital pavilion facets and to do them right takes a lot of room.
This means that they are going to be at least 65% and more likely the higher 60's low 70s to be well cut and display the proper patterns.

 

[strmrdr]

Date: 2/8/2005 10:12:20 AM
Author: valeria101

Date: 2/8/2005 10:1:50 AM

Author: Asschman


I am trying to determine whether the trade-off of the extra faceting is worth the larger table size

Glad you brought this up.... I don''t think it is a ''trade off'' - the extra steps compensate somewhat for the ''flat'' look that a large table would produce. Besides, 60-ish is not that big.


The most visible difference that extras cannot compensate would probaly (but not necasarily) be some loss of dispersion and (surely) the prominent crown showing in mounting.


If brilliance is good and those ''steps'' show I woudln''t necesarily cry for the old cut recipe. New ones are nice too

Just IMO, as usual.

Well said val :}

 

[Asschman]

Well I am happy to report that after some intensive internet sleuthing, I located three stones that all have the high 50s low 60s tables with the extra faceting. Very excited to see them, providing they are available.

Just to make sure I understand what Strm and Ana are saying--the larger the table, the less chance the crown will be sufficiently angled to get the right fire? So with a smaller crown, and the requisite deep depth, the crown angle percentage should have a better chance of being in the 10-15% range--at least in theory?


Asschman

/remembering now why I hated geometry, and math in general

 

[valeria101]

Date: 2/8/2005 10:45:57 AM
Author: Asschman

Just to make sure I understand ---the larger the table, the less chance the crown will be sufficiently angled to get the right fire? So with a smaller crown, and the requisite deep depth, the crown angle percentage should have a better chance of being in the 10-15% range--at least in theory?

Er... something like that.... small table would mean high crown in theory, ''cause the crown angle cannot get very flat.

Imagine the crown is approximately the bottom half of a pyramid between a section through the girdle and the table - this approximation is not great for step cuts, but this where the "tradeoff" between crown height and table size comes from. (Garry''s HCA does this for rounds, but the approximation works way, way better for brilliant cuts).

IMO, once the table % is not either really small or really, really big - this theory doesn''t hold well. That 60% table on a step cut may well mean 7% or 20% crown height. Both are out there are would look quite different. Neither 50% table with crown height below 10% or 70% table with crown over 15% are very likely.

I really wish someday someone would put up a detailed tutorial about these things. I don''t know nearly enough to do so

 

[maddogmadden]

Date: 2/8/2005 10:45:57 AM
Author: Asschman
Well I am happy to report that after some intensive internet sleuthing, I located three stones that all have the high 50s low 60s tables with the extra faceting. Very excited to see them, providing they are available.

Just to make sure I understand what Strm and Ana are saying--the larger the table, the less chance the crown will be sufficiently angled to get the right fire? So with a smaller crown, and the requisite deep depth, the crown angle percentage should have a better chance of being in the 10-15% range--at least in theory?


Asschman

/remembering now why I hated geometry, and math in general

Nice to see that you are looking for an asscher with the extra step cuts. I just bought one with five step cuts in the pavillion and I really think it helps give the asscher a bit more fire etc. More importantly, when I have compared a four or five step cut asscher to a typical three step cut asscher the biggest difference is that the five step has that deeper look, and the repeating pattern when you look into the table is easier to see. Just my opinion.

 

[Asschman]

Date: 2/8/2005 12:15:38 PM
Author: maddogmadden

Date: 2/8/2005 10:45:57 AM
Author: Asschman
Well I am happy to report that after some intensive internet sleuthing, I located three stones that all have the high 50s low 60s tables with the extra faceting. Very excited to see them, providing they are available.

Just to make sure I understand what Strm and Ana are saying--the larger the table, the less chance the crown will be sufficiently angled to get the right fire? So with a smaller crown, and the requisite deep depth, the crown angle percentage should have a better chance of being in the 10-15% range--at least in theory?


Asschman

/remembering now why I hated geometry, and math in general

Nice to see that you are looking for an asscher with the extra step cuts. I just bought one with five step cuts in the pavillion and I really think it helps give the asscher a bit more fire etc. More importantly, when I have compared a four or five step cut asscher to a typical three step cut asscher the biggest difference is that the five step has that deeper look, and the repeating pattern when you look into the table is easier to see. Just my opinion.

Long time no see Mad dog

I had actually sent you an email or private message to find out more about your experiences looking for a 4-5 facet asscher. Do you have any photos you could share, or info on where you got it?

Asschman

 

[maddogmadden]

Hey there. I can''t exactly figure out how to post pictures. One way to find a five step asscher is to run a search on pricescope and then try to view the certs. You''ll notice that a lot of the vendors have the same diamond. It takes some time but you can get lucky. Also check with Diamondsonweb.com. They seem to have quite a few four and five steppers. I believe they use a cutter who cuts the asscher this way. You can have the diamonds sent to your local jewler to view although you''ll pay more to do this. (of course make sure that all the other qualities of a good asscher are there)

Your best bet though is to try to work with a small jewler who can find the diamond you are looking for. I live in Chicago and was able to work with a jewler who would basically get the diamonds that I''d found on the web. He was able to have them sent to Chicago so that I could view them. He was also able to get me a better price which was nice. He did not charge much because he admitted that all he was doing was getting me the diamond. I told him I would of course work with him on buying the setting and wedding rings. He was also able to call all of the big wholesalers to find out if there were any five step asschers.

Hope this helps and sorry for any typos.

 

[maddogmadden]

one thing. if you can afford it, try to get an asscher that is a bit under 1.5 instead of a 1.0 ct asscher. My experience is that with a 1 ct. you just cannot see much of the steps or repreating patterns, even if it is well-cut. Plus, as you know, a 1 ct asscher is smaller than a 1 ct. round.

 

[Asschman]

Date: 2/8/2005 5

7:52 PM
Author: maddogmadden
one thing. if you can afford it, try to get an asscher that is a bit under 1.5 instead of a 1.0 ct asscher. My experience is that with a 1 ct. you just cannot see much of the steps or repreating patterns, even if it is well-cut. Plus, as you know, a 1 ct asscher is smaller than a 1 ct. round.

Mad dog, thanks for your input. I did figure out that by looking at the same stone at different web-based vendors inventory you could get a determination of what type of cut the stone was, and the GIA plot diagram showing the different faceting. Unfortunately, if I want to get engaged this year, which I do, then the 1.11 I am calling in will have to suffice. Maybe since I split the difference with 4 facet steps versus the 5 in your stone it will be ok.

As for attaching photos, check out the top part of the response form where it says attach file. I had some trouble putting pictures on the page, but if you have it in the right format--jpeg should do--then it should work. Alternately, I could provide you with my email address and you could attach it that way.

Cheers

Asschman

 

[maddogmadden]

Hey there. 1.11 ct sounds great! If you can, check to see if there are any small diamond jewlers who would be willing to help you out. You might be surprised that they can get you a better price than on the web. Basically, the jewler would call and get the diamond for you so that you could see it before you purchase it. Also, they might be able to get a few more for you to help compare. It''s nice to be shown, say, three asschers at once to see which one you like best and then look at the certs. Looking at the diamonds is especially important because it is an asscher cut. Good luck! I may be popping the question this weekend!!!