Some find this reduction colour a little fussy but it definitely rewards patience. If worked into the centre of your bead and combined with silver, you can get some rich green boro tones as shown in the bead set by Lisa Jordon. Lisa used a gather of Iris Amber layered with silver and clear. The gather was then combined with silver, pulled into a stringer, and laid over a base of black.
When left on the surface and reduced (more propane, less oxygen) caramel brown metallic colours emerge.
Use sparingly since it darkens after annealing.
Always use a non-reactive, neutral base. Avoid Moretti Ivory as it's too reactive.