The MegaScope

Well... when introducing this new piece of lab equipment I thought what better place to put this page than after the AGS000 page. The reason for this is because all teaching to this point have been based on cut analysis according to external data (ie. proportions/polish/symmetry) which do impact the beauty and look of a diamond, but as you'll see after this page there is internal analysis I perform here as well at the UDIS.

Concerning the cut quality of a diamond and where it falls on the AGS cut scale, 99.9% of John Q. Public, if he asks, is usually presented with a document called a Sarin analysis. This is particularly helpful (and in my opinion quite necessary) when looking at diamonds that are only accompanied by a GIA report. As the GIA report does not provide the data necessary to determine cut quality the Sarin proportion analysis give us some very critical information we can use to form a judgment on the diamonds cut quality. The most common proportions analysis look like this.

Here we have the crown & pavilion data lacking from the GIA report. This information can also be found on the AGS reports so if a diamond is accompanied with an AGS report we wouldn't necessarily need the proportion analysis provided above. In the top right corner of the AGS reports we find the actual proportions for a diamond listed as well.

So far so good right? ;) Ideal cut goodies in the pic above. All specs fall within that cherry "0" range of an ideal cut diamond. Well... there's more than meets the eye here. Let me explain. See the crown angles above which are 35.1º? Well... most people are under the assumption that each of the 8 crown angles of the diamond are all 35.1º. WRONG! 35.1º is an average of all 8 of the crown bezel (kite) facets going around the diamond. So one angle might be 33º, one 37º, one 35º and so on around the stone, with some of the diamonds angles and proportions EVEN FALLING OUTSIDE THE IDEAL RANGE! The truth is the diamonds angles (crown and/or pavilion) can have such large variances which can reveal that what we thought was a precision cut ideal cut diamond was indeed the sloppy handiwork of an amateur. How are we to find this out?

Advanced External Cut Analysis

As you look at the report below we see some data not found in the above analysis. Let's use the example again of crown angles. This diamond below has average crown angles of 33.8º. The ideal range is 33.7º-35.8º, so 33.8º is just fine. Note the number in parenthesis next to the 33.8 reading below. It notes (33.4 -34.3) meaning that around the diamond, the minimum measurement of crown angles is 33.4º and the maximum crown angle measurement is 34.3º. A .9º variance from min to max crown angles which in itself is not bad at all EXCEPT FOR THE FACT THAT 33.4º IS NOT IDEAL! How many of this diamonds facets fall outside the ideal range? Check out the next graphic below.

In the graphic below the facets are numbered 1-8 starting with the bezel facet at the 3:00 position. Note the crown angle at facet 1 is 33.5º. As you go around the diamond you'll note crown angles are listed in dark blue ink ... when the color changes from dark blue to green ... the green indicates facets that fall out of ideal specs. Note facets 6 & 7 ARE ALSO OUT OF IDEAL RANGE. So what we have here are 3 facets on this diamonds crown angles that are not even ideal. It's your money dude ... and if we are going to shell out the bucks for a so called *ideal cut* diamond ... at least let ALL ITS FACETS BE IDEAL! Not some, not most ... ALL. Another thing to take note of in this example is the variances in the measurements taken.

As already noted the variance from minimum to maximum crown angle is a difference of .9 degrees. Let's also note the rest.

Facets measured	Variance or difference from minimum to maximum
crown angles (33.4 - 34.3)	.9º
crown height (14.3 - 15.5)	1.2%
pavilion angles (40.1 - 41.4)	1.3º
pavilion depth (42.2 - 43.3)	1.1%
table % (55.2 - 56.5)	1.3%
culet off centered	.6%
table off centered	1.0%

While this isn't what I'd consider terrible, note that many of this diamonds variances are at or over 1%/º plus the fact that a few of it's measurements fall outside the ideal range altogether. Before dropping the bucks on something like that I familiarize my clients with what I consider to be cherry precision. Imagine most or all of the diamonds proportions/angles falling less than 1%/º variance with ALL MEASUREMENTS in the ideal zone? It's out there friend ... what we have to do is a little hunting. :)

For the remainder of this advanced cut tutorial and the reports I generate with the MegaScope digital proportion analyzer, I will be using an example of what I would consider to be one of the most precision cut diamonds as my example. This is the kind of diamonds I stock on a regular basis. :)

Well ... you've already become familiar with these first 2 reports shown here. Take a gander at this diamonds variances. *<]8-) (hehe... that's me with my party hat!)

While you still have the chart above fresh in your heads ... let's see this diamonds breakdown. :)

Facets measured	Variance from min to max
crown angles (34.2 - 34.4º)	.2º
crown height (15.0 - 15.3%)	.3%
pavilion angles (40.7 - 40.9°)	.2º
pavilion depth (42.6 - 42.9)	.3%
table % (56.2 - 56.5&)	.3%
culet off centered	.1%
table off centered	.1%

NOW YOU TELL ME ... WHICH ONE'S THE CHERRY? *<]8-) Which is the more precision cut diamond? Let's see the rest of the reports I can generate for ya on this and I'll explain each one for ya. Just a note though ... all the reports are at my disposal on each diamond I carry but what I'll be posting publicly will usually be either the above or this one below as it gives all the pertinent data you'll need to know. The rest is alot of techie stuff but useful nonetheless.

This next one here shows us the additional data of the diamond on a facet by facet basis showing each individual crown angle/height measurement, pavilion angle/depth measurement, girdle thickness measurements all around the diamond & girdle graph showing min and max girdle measurements, table/culet off centeredness, etc (which you'll see more blown up and detailed versions of this in a second).

The next report is a top down report. Note that crown/pavilion angles are written in red, crown/pavilion depth percentages are written in blue and the table measurements in green. This makes for easy separation for what data we're actually looking at. :)

This next one here is just an averages graph. Typical of what we'd find on an AGS report of more simplified proportion analysis.

This next one shows an how frequently the diamond is off round. This diamonds minimum and maximum diameter measurements are 6.48mm - 6.50mm which is far from being "off round" but seeing the data is kinda neat. Perhaps I'll have to post a kaka diamond after this to let ya'll compare.

This next report shows me how well the pavilion main facets are aligning with their corresponding bezel facets on the crown. In this diamond ... all facets matching. :)

This next report shows me exact girdle thickness all the way around the diamond. One very important thing to take note of here is this. When you see the girdle thickness listed on a report, be it AGS, Sarin, etc ... WHAT THEY ARE LISTING IS THE GIRDLE THICKNESS (minimum & maximum) AT THE VALLEYS. Not the bezels or the halves. To see what the bezel, halves and valleys are around the circumference of the diamond see the next report. From this report however we can see how nice and even this diamonds girdle was cut. There is no waviness to it at all and it's nice and consistent. Note the minimum and maximum thickness at the girdle/bezel%.

This next graph shows us exact girdle thickness from point to point around the diamond as well as the length of the star facets and how far they extend to the girdle from the table.

This is some neat stuff huh? You bet! hehe... I was thinking of naming this page "For Cut Geeks Only". If you've read through this and are interested in this data when it comes to making your purchase and YOU KNOW you want a true precision cut stone, just confess it to me up front ... Jonathan ... I'll admit it! I'm a cut geek! =) That'll give me an idea of what you're looking for in cut quality. ;-)

Now ... one reason why I wanted you to take note of the min/max girdle thickness at the bezel is this. If you look at a Sarin analysis average graph (like my very first graphic at the top of the page) you'll see it says 2.5% .016mm. THAT IS THE AVERAGE BEZEL GIRDLE THICKNESS. The diamonds girdle thickness (listed to the left of it) says 1.0 - 2.0%. 1.0 - 2.0% is the diamonds girdle thickness from min to max in the valleys. In this example down here, if you go to it's average graph you see it lists in the profile graphic the diamonds average girdle thickness at the bezels while listing it's min & max girdle thickness at the valleys. Had enough? Me too!

This last report are the hard cold numbers on the diamond from crown/pavilion main facets 1-8 along with minimums, maximums and averages.

Now that we've finished the external cut analysis ... on with even more interesting things. The Internal analysis. :) Click on next to proceed.