Hi David, welcome to CDI. Diamonds by Lauren specializes in NATURAL colored diamonds. As I understand it, unless it is by special request, or a very special stone, it is not David's intent to stock treated diamonds. Since you are asking about methods of color treatments, I assume you are looking for a treated colored diamond? Or, perhaps, you are just doing your homework to assure you do NOT purchase a treated colored stone?

Regardless, I can tell you that there are many ways to add color to a diamond, some are more sophisticated, permanent and accepted than others. And, when it comes right down to it, if you are spending any sort of significant money on a colored diamond, it is best to have it accompanied by a report from a legitimate lab, like the GIA. New methods to treat gems pop up everyday and are becoming harder and harder to detect.  Most people, indeed most jewelers and appraisers, do not have the knowledge and equipment necessary to test for all the modern methods for color enhancement. Recently, there have been some very large, pricey diamonds that were thought to be natural; however, after GIA examination, each turned out to be treated (and worth much less than someone paid or was about to pay for them).

A most primitive method for coloring gems is by coatings. Chemicals are applied, or coated, to some pavilion facets, around the girdle, or on the culet. This method is usually hard to see on mounted stones ans somewhat easier to find on unmounted diamonds. Coatings are not permanent, and not considered desirable. Also, fracture filling (filling diamonds with glass) can affect apparent color, especially if the material is damaged.

Irradiation treatments penetrate a diamond and change the color by altering the internal crystal structure of the diamond. Today, almost all natural diamond colors can be made by this method. This type of treated diamond is fairly easy to find (for purchase) and is generally considered acceptable, as long as treatment is disclosed. The downside is that once treated, extreme heat (when a jeweler heats a prong for repair, or removal of a diamond, for example) may affect irradiated diamonds by changing the color again (to something undesirable).

Often, treated diamonds show a somewhat unnatural looking color. I think, at one time, David posted photos of some treated stones on the forum; perhaps you can checkout some of the older threads to find them.

Finally, as others on this forum have mentioned, green in diamonds, a color created by radiation in nature, is extremely hard, if not impossible, to determine to be man-made color or natural color in diamonds.  GIA will usually issue a statement to that effect on a report.

Huzzah for Trinkette!  Articulate, comprehensive... and rightly loyal/practical.  Nicely done!

Not to mention that natural colored diamonds are, in my opinion, far more beautiful than irradiated.

Take blue diamonds for instance. Now that I have learned from Diamonds by Lauren what a natural blue diamond looks like, I doubt I could be happy with an irradiated blue - which is what most of the more inexpensive blues you find in chain jewelry stores are. They have always looked off to me but now I know why.

It is the same for yellows and oranges. Irradiated has a really bright color but there is still something about them that makes them seem, to me, like they are colored rhinestones.

However, each to their own. I showed my stepmother what a natural blue looks like on the DBL website but she didn't care for them. She prefers the vivid color of the irradiated ones.

Here's a link to some of the most gorgeous colored diamonds I have ever seen (pictures of lol):
http://diamondsbylauren.com/