The Old Waldorf-Astoria Bar Book by Albert Stevens Crockett (1935, p.64)
| 1 dash | Absinthe | base |
| 0.5 part | gin — Plymouth gin | base |
| 1 dash | orange bitters | base |
| 0.5 part | dry vermouth — French vermouth | modifier |
- Stir and serve cold.
Opal is Plymouth gin, French vermouth, orange bitters, and a dash of absinthe.
The Old Waldorf-Astoria Bar Book by Albert Stevens Crockett (1935, p.64)
| 1 dash | Absinthe | base |
| 0.5 part | gin — Plymouth gin | base |
| 1 dash | orange bitters | base |
| 0.5 part | dry vermouth — French vermouth | modifier |
The Artistry of Mixing Drinks by Frank Meier (1936, p.35)
| 0.33 part | gin — Gin | base |
| 0.33 part | Pernod — Anis 'Pernod fils' | base |
| 0.33 part | dry vermouth — French Vermouth | modifier |
See also: Opal