Hindustan Petroleum Corporation (HPCL) and Gitanjali Gems have signed an agreement on co-branding to boost revenues.The idea is to offer a one-stop shopping experience for customers who make regular purchases at fixed places like fuel stations.As the first step of the alliance, Gitanjali Gems recently set up an exclusive outlet for its Sangini brand at an HPCL petrol pump in Kolkata.K S Rekhi, chief regional manager (retail) of HPCL, said: "Every second HPCL customer is a Sangini diamonds customer. So, if we are looking at a one-stop shopping opportunity for our customers, the brand fit is perfect."Manjunath Jyothinagar, president of the jewellery business of Gitanjali Gems, said: "By November next year, Sangini will set up close to 45 exclusive outlets - one at every HPCL petrol pump in India. Within another two months, we should be setting up close to five outlets at HPCL petrol pumps all over India."He said HPCL pumps were expected to yield annual sales of close to Rs 1 crore from every showroom of approximately 300 sq ft. Customers can also avail of free parking every time they walk into a Sangini store at HPCL petrol pumps, he added.HPCL petrol pumps also accommodate other brands like Cafe Coffee Day, Baskin Robbins, Subway, Crossword and ICICI credit cards at select locations.