| year of publication | ISBN | author(s) | title |
|---|---|---|---|
| 1993 | 978-0-9625311-3-2 | Paul B. Downing | Opal Adventures |
| '' | 978-0-9625311-4-9 | Paul B. Downing | Opal Cutting Made Easy (Jewelry Crafts) |
| 2001 | 978-0-9625311-5-6 | '' | Opal: Advanced Cutting & Setting |
| 2002 | 978-0-9625311-8-7 | '' | Opal Identification & Value |