The Pearl Diver is one of the more unusual Donn Beach drinks — its defining ingredient is a custom emulsion of softened butter, honey, vanilla, and warming spices, blended together and held cold, then shaken into the cocktail in place of plain sweetener. The butter is what gives the drink its name: the cocktail goes silky in the same way pearl divers were said to grease their bodies before going under. The recipe dates to 1937 at Don the Beachcomber and was reconstructed by Jeff "Beachbum" Berry from period notes; it appears in Beachbum Berry's Sippin' Safari (2007).
Butter in a cocktail sounds wrong. Then you taste a Pearl Diver and remember that a Hot Buttered Rum has been good for 200 years.
The Pearl Diver's Mix
The mix — sometimes called Pearl Diver's Mix, sometimes Gardenia Mix in surviving Donn Beach notes — is the recipe's defining element. The base formula: a stick of unsalted butter (4 oz / 113 g) softened to room temperature, blended with 1 cup of honey, 1 cup of allspice dram or pimento dram, 1 teaspoon of pure vanilla extract, a quarter teaspoon of cinnamon, and a pinch of clove. Blend until uniform, then refrigerate. The mix solidifies somewhat in the cold; let it come up to room temperature for 10 minutes before serving to make pouring possible.
The mix holds in the fridge for two weeks. It is the same general concept as the Hot Buttered Rum batter (butter + sugar + spices held in advance), but Donn used it cold in shaken cocktails rather than spooning it into hot ones. The technique is uncommon — almost no modern cocktails use butter — and the drink is unlike anything else in the tiki canon.
The Spec
An ounce and a half of Puerto Rican gold rum, one ounce of Jamaican rum, a half ounce each of orange and lime juice, and an ounce of Pearl Diver's Mix. Shake hard with ice, strain into a tall glass over crushed ice, garnish with mint.
Shake Vigorously
The butter in the mix doesn't dissolve at refrigerator temperature; the cocktail relies on the shake's mechanical action to emulsify everything. Shake harder and longer than a standard cocktail — 12-15 seconds, not 8-10. The result should be cold, slightly textured, and uniform in color.
Rum Choice
Puerto Rican gold (Bacardi 8, Plantation 3 Star) and Jamaican (Smith & Cross, Hamilton Black Pot) — same as the Zombie's first two pours. The 151 Demerara doesn't appear here; the Pearl Diver is a lighter drink, less reliant on alcoholic weight.
Garnish
A simple mint sprig is the published garnish. Some modern bars add a small slice of fresh pineapple. No swizzle stick is necessary; the drink should be drunk soon enough that the butter remains emulsified.
Bottom Line
The Pearl Diver is a once-or-twice-a-year drink: making the mix is a project, and you don't want to drink it more often than the mix itself stays fresh. But when you do open the mix and shake one — over crushed ice, with two solid rums — the result is unlike anything else. It is the strongest argument that butter belongs in cocktails.