Call for Help: What Kind of Paint Is Used For A Buddha Image’s Pupil?

Here’s a request for those in the know, or for those with access to Khmer monks who speak English (hint, readers in Cambodia!). Some of my monkly friends here in the United States need to know answers to the following questions:

• What kind of paint ought to be used to paint in the pupil of the central Buddha image in a Khmer Buddhist temple? (The painting is done in a ceremony called, in Khmer, “Bun Bark Netr” (or, “Open the Eye Ceremony”).
• Where get we get this kind of paint in the United States?

Any help at all on this will be greatly appreciated. Fire away in the comments!