Seeking advice on portfolio diversification

I'm meeting with my financial planner tomorrow, who I know is going to recommend diversifying my $GOOG holdings. Although I'm generally very risk-averse with my financial planning, I don't really want to sell my $GOOG stock for two reasons:

  1. I got it fairly low 4+ years ago and I see no signs that it won't continue to go up over time. Unless it completely tanks, the risk is essentially only getting even money out of it, and the gain is potentially hundreds of thousands of dollars.
  2. I work for Google and having the stock reassures me that if I get laid off, the stock will likely go up so it won't be all bad.

Note that my investments are currently about 50% $GOOG and 50% diversified through my financial planner, so not all my eggs in one basket, although it would be a huge hit if it went away tomorrow.

So give me your advice - if I'm truly risk averse should I diversify my $GOOG?