Their market share may be going down, but the Diamond Trading Company, the diamond marketing arm of the De Beers Group of companies, posted sales figures of US$ 6.15 billion for the year 2006 – its second highest performance on record, although it was dealing with diminished intake from Russia. Its net profits were $732 million, a 26% increase. So basically over 10% of their sales were profits.
However, a financial report from Charles and Covard, manufacturers of synthetic moissanite, found that its net income for the fourth quarter increased to $1.3 million, off of $12.1 million in sales. So they also have a profit margin of over 10%.
It is worth noting that the gross profit from manufacturing moissanite is $9.28 million. Their largest expense — $6.2 million — comes from marketing and sales. Unlike diamonds, moissanite is cheap to produce. Getting people to buy it costs a lot more.