>Finding diamonds is great but if you constantily have to give up 75% of it to get it poished and cut for market...well....

http://www.independent.ie/business/irish/exxon-woo-new-partners-to-allay-dunquin-drilling-costs-1295318.html

"By taking in a partner ExxonMobil is following a long standing industry tradition of spreading the risk on what is essentially a new exploration province."

BTW, they didn't "give up" 75% of it. The Exxon / MOL interest is 67% of 75% of the production license area.

"The Contract Area consists of approximately 184,300 acres, or 75% of Falcon’s 246,000-acre Production License. The Contract Area will be owned jointly, with Falcon owning a 33% undivided working interest and ExxonMobil owning a 67% undivided working interest."