Red Jasper Genuine is a medium reddish maroon colour according to Daniel Smith. It's a granulating, semi-transparent, non-staining paint with excellent lightfastness. Daniel Smith's stock of this pigment comes from India’s Gwalior region and is colored a rich red from iron.
Below's a comparison with other earth colours
The paper you use affects the granulation. The paper on the left is handmade 100% watercolour paper by Indigo ArtPapers. The right is Daler Rowney cellulose watercolour paper.
Red Jasper Genuine is not an easy colour to mix with and is best used on its own.
When added to Ultramarine and Phthalo Blue, it produces a muted violet or mauve-like colour.