Valuable items that have no use on Shabbat and that people always take care not to move except for the specific purpose for which they are designed (to ensure the items do not get damaged or lost) are muktzeh maĥmat ĥesron kis. For example, knives designed for ritual slaughter or for leatherworking are muktzeh. Even if one wants to cut his food with them, he may not pick them up (Shabbat 123b, 157a; SA 308:1).
Included in this category of muktzeh are: musical instruments, smartphones, radios, tape recorders, expensive or fragile music players, cameras, and mixers. These may not be used even for a permissible purpose, for example, as a paperweight. Similarly, one may not wrap himself in an expensive piece of fabric that has been set aside for sewing. In contrast, a valuable or fragile item that is frequently used on Shabbat, such as a gold watch, eyeglasses, or a magnifying glass for reading, is not muktzeh.
Other examples of muktzeh maĥmat ĥesron kis are paper money, important business documents, identity cards, credit cards, stamps, bus tickets, parchment to be used by a scribe, and stationery paper that is not used for any other purpose (SSK 20:20).
Wall clocks and valuable pictures, which people are careful not to move so as to avoid possible damage, are included in this category of muktzeh (MB 308:168). Also included are large free-standing closets that people are careful not to move without a good reason, for fear that they will fall apart (MB 308:8). The prohibition here is limited to moving the entire closet; one may open its doors and drawers, as they are meant to be used regularly.
Cups, plates, and clothes that are meant to be sold are muktzeh maĥmat ĥesron kis, since sellers usually insist that no one use them. If a seller does not insist upon this, his wares are not muktzeh. People who sell food generally do not insist that no one eat from their merchandise, and therefore the food in stores and warehouses is not muktzeh (Beit Yosef and Rema 308:1; MB ad loc. 6-7; SA 310:2; MB ad loc. 4).