I can't help you because I'm wondering the same thing 
*bump*
i found this in countrykitchensa.com :
Dusting Powders are available in:
Luster dust give subtle color with a sheen finish. In the dry form, use them for dusting. They may be used
on their own, or mixed with similar colored dusts to create a lustrous sheen without lightening the color.
Pearl Dusts produce a shimmery luster. Use super pearl on flowers made from colored gum paste. When
dusted on white petals, the other pearls in the range exhibit a subtle colored sheen by reflection, although
displaying no apparent color.
Sparkle Dusts hare a larger grain size with a sparkling finish. Gives gumpaste flowers a wet or dewy look,
with just a touch of color, except for white.
Petal Dusts are used to achieve deeper hues with a matte finish. When brushed on petals of white or pastel
gum paste flowers, a realistic effect is created.
Highlighters have a high sheen finish, and are available in silver or gold. They are non-edible. If wanting
silver or gold for edible purposes, use Super Gold and Moonstone Silver
were you looking at wholesalesugarflowers.com? they have pearl dusts and i thought they are the same colors...
Yes I was! I am going to try to make a fish cake like in Collette Peters book for a family birthday in a few weeks and went to order the luster dusts for it. I know I'm getting way ahead of my abilities but thought for the price it will be fun to practice without costing too much if it doesn't work out. I really thought it might be my eyes or my PC monitor though when I was looking at the pearl dusts!
yep, they are the same colors.. i wish cc will have more selections for dusting powders.. gudluck with your cake 
...do not forget to post the picture ok? 
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