Is the Cartier Tank Must Large Diamond a good first luxury watch?

Yes, if you want a recognizable dress watch with sparkle. It is simple to own thanks to the quartz movement, but the diamond bezel makes it less of an everyday beater than the plain Tank Must.

Can I swim or shower with it?

No. It is rated to 3 ATM, which covers splashes and handwashing only. Keep it away from swimming, bathing and the leather strap getting soaked.

How does it compare with the standard Tank Must Large?

Same case, dial and quartz movement, but this version adds a diamond-set bezel. The plain model is more versatile and understated; this one is dressier and more of a statement.

Does it come with a mechanical movement?

No, it uses a quartz movement. That means it keeps good time with minimal fuss, but you change a battery rather than winding or wearing it to power it.

What size wrists does the Large fit?

The Large Tank is a modest, slim watch that suits most wrists, including smaller ones. Try it on if you can, since the rectangular case wears differently from a round watch.