I use Sedgwick's leather for my dog collars, dog leads, belts and keyrings. I currently have 4 colours as seen in the photograph. The top colour is Hazel, the colour on the right is Black, the colour on the bottom is Burgundy and the colour on the left is Dark Havana.
If you are unsure on whether your choice of leather colour will work with your chosen thread, please send me an email and I can send you a photo of a sample of them together.