The server doesn't care what the glamour looks like. If you've unlocked it or not is a boolean value: true or false (1 or 0 to the processor & database). That's true no matter what it is. Set aside a 1KB chunk of space for every character, use a bitmask, and you can store if they've unlocked 8192 glamour items. That's how the crafting and gathering logs know every item you've made/gathered at least once to give you an unlock bonus.
(I am a programmer.)