I get VERY VERY VERY annoyed when presenters mislead. They've done this here and with the TP (see other thread). Right, here's the skinny ....
They did have a range of natural yellow and pink diamonds (as has been said before) BUT they were small in carat weight and set in 18k gold (generally). The pinks were pale and the yellows a lemon colour. This, I believe, was a one off range and the items were fairly expensive.
ALL OF THEIR
BLUE DIAMONDS are irradiated. Natural blue diamonds are
extremely rare and
extremely expensive. You can tell they're irradiated by their colour which tends to be a deep dark(ish) blue. To compare what GemsTV are selling to the Hope Diamond is incredibly misleading. Natural blues tend to be more pale. You can see some here:
http://www.amgad.com/Blue_Diamonds.asp
ALL OF THEIR
GREEN DIAMONDS are irradiated. Natural green diamonds are even more difficult to source than blues. If these were natural greens you could add on a few 0's to the price! Again, here are some greens, they tend to have a secondary grey, brown or yellow tone:
http://www.amgad.com/Green_Diamonds.asp
YELLOW DIAMONDS. I'm assuming the majority of GemsTV's yellows are irradiated. They certainly look it and the price would indicate they are. Whilst natural yellow diamonds come in all colours ranging from pale lemon to a vivid bright yellow, the price will indicate whether they're irradiated or not. All of the yellows I've bought from GemsTV have been irradiated with the exception of the natural range they brought out a couple of years ago. These were heavily marketed as natural and confirmed as such by SteveA.
PINK DIAMONDS. If pink diamonds are tiny (i.e. like accent diamonds) they
could be natural but if I'm not mistaken, when selling the latest crop of pinks they were very careful not to mention whether they were natural or treated. I actually phoned and was told they were irradiated.
NEARLY ALL
BLACK DIAMONDS on the market are irradiated. They used to be used for industrial purposes but have crept into jewellery more and more.
BROWNS/CHAMPAGNES/COGNAC and all the other "brown" fancy diamonds are
usually natural. No idea if this is the case with GemsTV brown range but I would presume so. As Sacha says, these are diamonds of very little value and were considered worthless a while ago. However, I have to say that larger browns (i.e. .50ct and above) CAN be very beautiful and have wonderful fire.
Hope that helps.