Drawing and colour experiment, including gold paint:
Final colour choices with yellow paint instead of gold:
Spring mandala on Arches Hot Pressed watercolour paper using Winsor and Newton Artists' Water Colours:
The colours in the scan above are not very accurate, so I tried a photograph. After some adjustments in Affinity Photo, I got this result, in which most of the colours are accurate, but the paper looks pale violet and the yellow is too dark, especially the border. Try to imagine a combination of the two pictures.