Stress
When your job involves being surrounded by sparkly rocks and mushy engaged couples, there's not much stress.
Unless, of course, you accidentally take too much off a diamond while cutting it for a setting, decreasing the value by thousands and thousands of dollars. Or if you botch a big appraisal for your boss and risk losing your job if he finds out.
Not. Much. Stress.
Other than those scenarios—which would be pretty stressful—gemologists don't face a lot of day-to-day stress. You might have to deal with a crabby customer or some rush-hour traffic, especially if you're making regular trips to New York's Diamond District for a client pickup/drop off, but that's the sort of stress that pretty much everybody faces. That's not so bad.