Swarovski has called this the "noble" color due to its understated shine and undeniable elegance. It is an intriguing 'barely there' color that makes it so compatible with tonal matchings and color combinations. It brings a refined nobility and elegance to its applications.
Some have said that the new 2009 color Greige and the existing Black Diamond is very similar. In my opinion, to the naked eye, they are indeed. Especially in the smaller sizes. But it all depends on the lighting. There are indeed differences - and it could be the difference that makes all the difference.
Here I have included a comparative shot of both 5328 XILION bicone beads - taken in natural light. You can clearly see that there are indeed differences.
Additionally, I heard from my Swarovski representative (on 16 Oct 09) that the sales of the Greige is expected to bypass that of the Black Diamond and may become jewelers first choice in the "almost there" range in grey tones.
Addendum: (added by request. Click for larger image.)
This additional photo shows 3 colours that some think look similar: Greige, Black Diamond, and Silk. However as I didn't have Silk on hand, I have shown Silk AB instead. It is still enough to show that indeed there are vital differences among the colors.
However you may have noted how the colours can vary (from picture to picture). That is one of the wonder of blings, Swarovski, and crystals - there is no one static colour and tone. It varies according to light and surrounding ambience.
From the Merriam-Webster Online Dictionary:
Pronunciation: \'gra(zh)\
(hear audio pronunciation of greige)
Function: adjective
Etymology: French grège raw (of silk), from Italian greggio
Meaning: being in an unbleached undyed state as taken from a loom —used of textiles