- Gin and tonic is a highball cocktail made with gin and tonic water poured over a large amount of ice. The ratio of gin to tonic varies according to taste, the strength of the gin, other drink mixers being added, etc., with most recipes calling for a ratio between 1:1 and 1:3. It is usually garnished with a slice or wedge of lime ¹. The origins of this drink can be traced back to pre-1900s India as a cure for malaria. Quinine, an extract from the South American cinchona tree, was used to prevent malaria and was drunk in tonic water but the bitter taste was unpleasant. British officers in India in the early 19th century took to adding a mixture of water, sugar, lime, and gin to the quinine in order to make the drink more palatable.