What adjective to use?

Well, it's a 3rd person narration, so as close to neutral as possible without sounding too clinical or dry.
Well, which of these two ideas seems more useful for this omniscient storyteller to convey: The idea that she thinks he's old, or the idea that he thinks he's old?

If you need it to be more detached (POV wise) than that, then just stating a number seems like the neutral way to go.
 
If the character is a man, using 'salt and pepper beard/hair' also gets the point across.
At least for me, I was at the very end of the range before I started to go salt and pepper in the beard. (Unfortunately, I seemed to be allergic to the pepper these days, and I have a salt + salt beard now)
 
Meanwhile, I got my first grey streaks in the beard in my late teens (I occasionally wasn't carded as a 19 year old) and full salt-n-pepper in the beard and hair by my mid-30s.
 
Yeah, my SO has had a salt and pepper beard since his mid 30s, and only just got his first gray hair on the top of his head.

While I got my first gray hair at 29.
 
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