This is why some lusters can only be decorative use only
Luster Dust gives subtle color with a high sheen metallic-like finish. They may be used alone or mixed with similar colored matte dusts to create a lustrous sheen without lightening the color. Brushed on white, they exhibit color and a metallic-like sheen. For a deeper more intense color mix with Lemon Extract and brush on. Contains two or more of the following: Titanium Dioxide, Iron Oxide, Carmine, Mica. Not water soluble. Colors will vary slightly from actual colors due to monitor variations. Please note the colors indicated by * contain Iron Blue or Chromium Oxide and must be labeled "for decorative use only."
The following two links label which one you can use and which one are not edible.
Now the Nusilver that show you can use as edible use. Click on the color from country kitchen and in the desciption they will tell you if you can use as edible or decorative. Sugarcraft has their marked by "*"
Hope this helps you, some place mark are luster decorative only because it is not fully approved by the FDA. Sugarcraft does have have dust that is approved by the FDA if it is luster you will have to check.