Gemma Labs is raising cash to support increasing demand for its Gemmist custom shampoo service. The Seattle startup reeled in a $2.75 million round from PSL Ventures and other investors. Gemma Labs spun out of Pioneer Square Labs’ startup studio more than two years ago and raised $3.5 million in April. The company reached $1.5 million in annualized sales last year. Gemma Labs uses in-house scientists to concoct special shampoos for individual customers, based on surveys they take that assess individual hair and scalp needs, in addition to seasonal factors.