Treasured describes something you hold on to and look after because it means a great deal to you — a treasured photograph, a treasured friendship, a treasured memory of your grandfather. Note where the value comes from: not from price, but from feeling. A treasured object may be worth nothing at all to anyone else, and that is quite normal, even typical. It sits before the noun almost every time ('her most treasured possession'), and it carries a soft, warm, slightly formal tone, so you see it in speeches, obituaries, letters and dedications more than in daily chat. It is also the past form of the verb treasure — 'I treasured those afternoons' — which means to value something deeply and keep it safe. In that verb form, people often say 'I'll treasure this' when someone gives them a gift, and it is one of the kindest things you can say back.