Knowing what I know now, I would not trust myself at 18 years old (or even 21) with a Rolex.
My first watch was a gift. A Seiko Digital alarm (steel with steel bracelet) that I got at Form 1. I smashed the crystal on that thing at least twice and when it finally died 11 years later, it was VERY BEAT UP - basically destroyed.
My second "real" watch was also a gift. A
TAG Heuer 2000 quartz model (the one with Mercedes hands). Even though I was working on my first job by then, age 20+ ; I took a lot of liberties with it. Cracked the crystal at least once, forgot to screw the crown and had water in the watch; I even lost the watch for several months until I luckily found it again. It's a wonder that the watch lasted as long as it did until I seriously looked into collecting watches (at a ripe of age of 30++.)
The things is, unless you really really educate and trust your kids; "what is gotten easily is not as valued."
A Rolex watch on a teenager IMHO is not a good idea. It just makes your kid a target. Even past 21, it will depend on the maturity level of the person. I think maybe landing a good job might be a good start with that watch.
Unless they really are interested in watches etc., chances are most kids nowadays will take things for granted. Like giving the keys of your prized BMW or Mercedes to a 18 year old kid who just got their license. Their inexperience will probably result in a dent or two in the car before long.
Just my thoughts.
