GUILT-FREE GLAMOUR!® To celebrate our 43rd Mannivesary, we’re offering Amethyst Ashes with limited edition artwork by John Holstrom for a special price! Amethyst Ashes is a smoky grey hair dye with cool purple tones. For the most radiant results, we recommend lightening hair to the lightest level 10 blonde before use. How many 4oz containers of Manic Panic hair color should I buy? Short Hair up to Bob Length: 1 jar/bottle for thin or thick hair. Below the Shoulder up to Waist Length: 2 jars/bottles for thin hair and 2-3 for thick hair. Tailbone