Legend has it that the mermaids of old used to dye their scales with crushed ancient sea sponges. It's a method that requires some elbow grease, but the results are worth it.
However, be warned: this method is not for the faint of heart. It's a risks involved in handling the sea sponges are not to be taken lightly.
For the modern mermaid, there's a simpler way to maintain those scales. Simply mix and match Mermaid Scale Paint with some Mermaid Scale Varnish for a truly magical effect.
But don't forget to read the instructions carefully, or you might just end up with a batch of failed mermaid scales.