There is a lot to gemology, and what you are asking could fill
several books. Here’s a brief take on it: What I’d like to know is :
What to look for when buying a good quality versus a poor quality
The typical 4 c’s — clarity, cut, carat weight and color —
generally determine price. In the case of colored diamonds, there
are preferred shades and different colors are less or more valuable.
Prices for these stones seem to be all over the place and I’m not
sure why one stone may be triple the price to a similar much cheaper
See above. Also, there is no law that says that some dealers will
not charge more than others for equivalent stones.
What should one expect to pay for these stones?
Diamond appraisal is a tricky and complex business. You need to have
the diamond graded (or grade it yourself) first and then you have to
have access to price research to establish a price. The Guide is a
pricing guide for diamonds and colored stones that is put out by
Richard Drucker. It will have updated prices (each quarter) on all
the gemstones and a reference manual with it that includes standards
for color and clarity grading. You can also find a couple of manuals
that teach diamond grading. I would check the on line GIA bookstore,
although I wouldn’t necessarily buy new from them. Check Amazon or
Are inclusions acceptable and do they affect value?
Inclusions are a fact of life with diamonds. How “acceptable” they
are depends on their visiblity and how rare the diamond is. A deep
red or blue diamond that has not been treated is going to be worth
some pretty good money even if it is somewhat included. very cloudy
or included diamonds are downgraded considerably.
Are some colors more valued than others?
Yes, look into gemology texts and the Drucker’s manuals for the
How to work with these types of stones. Are they as hardy as their
more brilliant counterparts?
All diamonds have the same hardness and cleavage. So yes, but you
can chip or cleave them in setting. If you are asking about cutting
them, that is a very specialized trade. There are a couple of manuals
about it, but it takes years to learn and thousands of dollars worth
of specialized equipment.
How do they get their colors?
Nitrogen (brown and yellow) and boron (blue) trace minerals and
plastic deformation of the crystal lattice in most other colors. You
need to consult a good gemology text for more info.
Good sources for purchasing these stones.
Check at gemology on line for further discussion and possibly
someone will have some sources. Colored diamond rough is going to be
pretty hard to find.
Any other practical and sources of
I think there is a diamond cutting manual by Basil Watermeyer. A
good place to ask further questions would be at the gemology on line
A couple of the world’s best gemolgists post there as well as folks
plugged into the rough stone market. Be aware that this is very much
a small niche where only a few have and many are not
disposed to sharing. Also, as I noted above, it’s a rather complex
subject that doesn’t have easy answers. You’ll need to study quite a
bit to know much about it.