Is it worth it

[Greenbean]

To try to get alexandrite from fates? Are they just as rare as atma?

[Avarghaladion]

From what I've seen, they appear to be at best as rare as Atma... though I've yet to see one drop for someone. Probably only worth doing if you need to finish your companion's 100 kills for the weekly challenge log exp boost.

[TomTom1968]

Not really worth it. When the Patch came out, I did it with a few FC mates for at least 5 hours in a row...none of us got one. Since 2.3, I have gotten 2 Alexandrites in total from maybe 200 FATES I have been in (gotta kill some time while waiting for hunt mobs). If you look for extra Alexandrites, both the Hunt and Myth grind are more viable options.

[Theresa]

I think it's worth it because of the Seals. You can make Gil just selling stuff you can get with seals, including Ventures.

[Kaven]

Just as rare if not worse, got 1 from about 8 hours of random grinding. You're better off grinding Myth and buying a map.

[Maero]

Not worth it at all. It may take you a year to get them all, this based on my current experience of getting a atma weapon for my blm.
Myself i am just getting the daily quest in mor dhona that you must do expert roulette in order to get map. You get myth, gil and a map.
Also myth is so easy to come by now you can always just spend 800 myth on one as well if our in a hurry for Alexandrite.