Edit color swatch thumbnails

[sibouss]

I am building a jewlery store and have different color options such as gold, white gold, rose gold, etc... At the moment my theme is fetching those colors and displaying them as flat colors that don't represent the actual variants. For example the 'gold variant' display a flat yellow color

Is there a way to customize the color swatches to be more accurate?

My store 578f0e-a2.myshopify.com 

Ideally for example for gold, I'd like to display something like this: