Depends on the conditions, tropical environement effects it, if its been out on a shelf exposed to heat and humidity (ie house with no AC open to the conditions outdoors) vs a case stored inside in a storage room somewhere in your house, which isn't exposed to the conditions, then the black stays black and doesn't change color If one step in the process for coating these is off and not suitable to these conditions, the browning or tropical look can occur easily over time and with the right "luck" from your environement, when you live in a tropical climate it occurs much easier. You could also have in theory a perfectly coated example that has just withstood harsher conditions in life than other pieces and therefore due to the chemical reaction with the environement either fading or distressing of the color can occur It all depends on your environment A Great example is leaving a Yellow Flag outside in the environement on a flag pole and keeping another example in your drawer, which one would become more faded through time the environement and reaction to sun, heat, cold etc would all effect the color of the piece while the one that is protected and not used would remain close to New Old Stock. Other examples where this can occur is watches and guitars, a lot of musicians that go to record in the Caribs either bring an alternate or don't take their prime examples with them, because the strings can rust and through time the guitar's finish can fade.