I adore cashmere!
I have a prada short-sleeved sweater, just plain jane beige. Honestly, NOT worth the $$$. I mean, it's nice and all but there are so many other options
Loro Piana is the absolute best, nice selection and always always top quality
Malo a bit cheaper, also good but can be a tad boring
Ballantyne, traditionally english, can be funky and a bit eccentric, also great quality
Lucien Pellat Finet - very expensive but if you're looking for a sweater with a difference and youthful appeal, go for it, but can cost like 2500$
There are also cheaper brands, like Pringle of scotland, Heartbreaker cashmere, Braude, Ralph Lauren, TSE.
Than there is supercheap like Uniqlo and they're not actually bad.
But again, if you want lasting-power and not just a famous name, go for companies that specialise in knitwear.