Optical rotation sounds complicated but it’s actually about making sure essential oils have the correct terpene compounds. This is important because essential oils might not offer the support you require. Calypso Essential Oils do not guarantee purity. Calypso Essential Oils have been tested by an independent lab. Calypso essential oils also offers Optical rotation results for single essential oils. These results are available at sourcetoyou.com, by searching for the lot number on each oil bottle. To ensure safety for your loved ones and yourself, essential oils must be tested for purity.