Can knowing too much make you lose money?

I was speaking with a gemmologist today.... An expert in gemstones, who's seen all facets of the gem trade, from traveling around the world looking for gems, running his own small mine, and running his own store.... He said something intriguing....

He said, the people who make the most money with gemstones DON'T know all the details behind the gems. They DON'T know very nook and cranny of knowledge, how ever little defect of the gem is caused, what processes deep within the earth created the features of gem you admire in the glass case of the jewelry store....

He said, those who know too much seem to lose their ability to sell!

It reminds me of something Gordon said.... When he was selling hi tech sound systems (I think), he didn't need to know all the details of how the thing worked, since that's not what people bought.... They bought what it did for THEM (the benefits)....

Before today, I never heard so explicitly that knowing TOO much can hinder your ability to sell (since it takes your focus off of what's important).... But now it rings true. What do you think?

Dien (the knowledge-sponge) Rice