Hi, this is really a general question, but I have a washed buffalo hide Prada bag in the 'pervinca' (powder blue) colour. It's gone a bit yellow after a year's daily use, no specific stains, it's just generally getting a bit shabby. Any ideas? I'm scared to ruin it because a lot of leather cleaners can't be used on certain soft leathers, and because it's so light in colour, I don't want to risk it!! Help!