Clean The Leather 

Both of these cleaners are great for the leather leashes.  They make the leather waterproof, they keep the BLING in the Metallics &  the reds will not bleed when treated with these.  They can be found on, very reasonably priced.  Don't let your leashes get grungy,  or your dogs pink, use one of these cleaners and the leather will look and feel better.