Status Symbols

What substances or materials in your world are considered to be purely cosmetic high status or luxury items?
Tailored Clothing (everywhere); this is largely because people in The Garden come in such a wide variety of shapes that common fashion is fairly medieval. Most people wear unisex, loose fit clothes to work and live in, with a few nicer pieces for feast days or special occasions. If someone has had the time and money to have their wardrobe fitted to their particular, twisted frame, you know they're someone important/rich.
Horses (for all tribes EXCEPT Equine); because the Equine tribe consider horses their patron spirit, and they bond with individual horses as spirit guides, any nation wishing to keep on good terms with them has banned the use of them as beasts of burden or for heavy labor. This means there's no large-scale breeding programs in place, and the only use they have is as very expensive pets/elegant transport for the uber rich. Largely the nations which aren't concerned with diplomacy with Equinus wouldn't ride horses anyway for one reason or another (ex. The Hive and The Deepwater Reach).
Deep-Ocean Treasures (for all EXCEPT the Sea People); includes meat harvested from the depths of the ocean such as Orbit Crabs or King Squid. Many reasons for this. A big one is transport once things are even dredged up. Another being that only Sea People can make these harvests, as their bodies can withstand the pressure.
Clothing At All (for Sea People); since clothes (except the tightest fitting) restrict swimming, Sea People eschew them with the exception of the nobility. Of course, theirs is quite well-fitted, in keeping with the above note on Tailored Clothing.
Non-Rationed Food (for Citizens of Light); as the Shining City is a walled city, with limited population and resources, food is rationed strictly and mostly consists of heavily-preserved nutrition bars. For most, this isn't a huge imposition- if you grow up eating freeze-dried veggie loaf, you have no idea what you're missing in a Sunday roast. But for the highest echelons, fresh-cooked and even gourmet foods are readily available. Essentially they get first pick of produce before it's processed- skimming the cream, literally. Because everyone is equal, except for the people in charge.