Hello Elsa
In your question, you mentioned the issue of quality and sweaters that pill and fuzz (that's the english expression for it). I have had sweaters by TSE and N.Peal, and some were terrific and others complete garbage.I would suggest the problem isn't a brand, but the ply of the cashmere itself.
A good cashmere sweater should be at least 4-ply, which makes a good, long lasting, soft cashmere sweater. The higher the ply, the softer, warmer, thicker (but never heavy like wool) the sweater. 8 ply and higher is wonderful; it is also extremely expensive, and usually used only by luxury brands. The higher the ply, the higher the quality, softness and durability, and, of course, price. I have seen cashmere go up to 12-ply- in a locked showcase at the store. I did not dare ask about the price.
Another consideration is country of origin. Cashmere used to only come from Mongolia; back then cashmere was extremely expensive-you could never find it at mid-range department stores or discount outlets. Eventually farmers figured out how to raise the goats in China (and also, if I am correct, parts of India); but the climate and diet is different, so the goats grow a different quality wool. (Think of fur- a Canadian beaver fur will be very different from a South American beaver fur- the climate makes the animal's fur/hair grow differently).
The laws on the labelling are unclear- if the label says "Made in China", it could be Mongolian cashmere that was only knitted in China, or it could be knitted in China from Chinese cashmere. As far as I know, no country requires the label to tell you where the fabric/yarn was made- only the content.
I believe Loro Piana, Filatura di Crosa, Cariaggi and Noro Cash are all excellent cashemere mills; they are all in Italy so if you are determined you could simply buy the cashmere from them (many people do, at warehouse sales, then re-sell them on EBay) and either knit, learn to knit, or pay someone to knit the sweater you want for you.