May 162013

I came across this 1.01ct diamond, bought it with plans to recut… but sold it for education purposes.

Most round diamonds cut these days fall within a certain range.  For example a total depth would normally be in the 58% – 64%.  These I would consider ‘normal’.  Sometimes the way a rough diamond is found a cutter may get creative and do something with a deeper cut to retain weight.

If a diamond is too far outside of this normal range it is going to need a recut, that is when I use the diamond recut chart to estimate what it will take to bring the diamond into acceptable portions and make it salable.

I could not believe my eyes when this one came in:

Wegiht: 1.01ct
Measurements: 5.8 – 5.9 x 4.44
Table: 56%
Total Depth: 75.2%


1.01ct diamond with 75.2% depth

Right away I can see something is off with this diamond.  A 1ct diamond should have a width of about 6.5mm, this one is only 5.8mm so I know the depth is going to be very wacky.  It might have a very thick girdle, steep crown angle or steep pavilion angle (or maybe all three!).

If you calculate the diamond depth, you get 75.2%.  This is mind blowing to a diamond guy like me.  A true first!  No problem, just use the diamond recut chart to get an estimate of the weight after recutting to find out what you will end up with when the problems are fixed.

Wait just a minute…  this diamond is so far off the norms the recut chart does not even go that high.  The recut chart maxes out at a depth of 70% in which case you will loose about 20% of the diamond.

So what happened, did this little guy get recut?  Nope, the proportions were so wacky a diamond educator actually bought the diamond as it is – as an example of how bad a diamond can be cut!  It’s life was saved and will be used as a demonstration tool for years.