Does anyone know how much cake an entire "thing" of luster dust will cover?

Someone has asked me to make a cake for a bridal shower in the shape of an engagement ring and they want the band to look metallic. I checked on the price of gold leaf (which I have never worked with) and it was way more than she was willing to spend.

Any ideas how to go about this and what to charge?

I am thinking of using a 9" or 10" round pan and then cutting out the center and contouring it to make it the shape of a ring and then using a smaller cake for the diamond.

I appreciate all of your input!

one jar will probably do it, but i would buy two or three to be safe.

I use 23K GOld Leaf a lot as well as the lustre dust..The leaf is difficult to handle. They will stick to anything and very, very soft for a sheet..You can get then for $27.00 per booklet. I got mine thru the internet. If you search "Edible Gold Leaf"