Halo-determining the size of the melee

[cherij0411]

Hi

I recently fell in love with a designer setting and I am going to be looking for a jeweler to recreate it as the setting is almost 11k and I do not want to buy the center stone from the local retailer. It is a chunkier halo. I have attached pics is there anyway to figure out how big the melee used is around the halo?

Thanks