Start by LIGHTLY inking your stamp. You don’t need much ink as the water will make it spread.
To add the water, I prefer to use a water brush. A spray bottle usually adds too much water and is hard to control. I just lightly dab the wet brush onto the ink and spread it around.
I stamped onto watercolour paper, creating a not-so-perfect background. Once dry, I took a white gel pen to add some simple details into each diamond.