Singhal had quit Ola in July, four months after he was elevated as TFS' CEO.
While Singhal could not be immediately reached for a comment, a spokesperson for Bluestone, which is run by Bangalore-based Jewels Online Distribution India Pvt Ltd, confirmed the move.
Singhal is expected to report to Gaurav Singh Kushwaha, Bluestone's founder and CEO.
Singhal had become TFS's CEO after the company was acquired by larger rival Ola for $200 million in March. His elevation at TFS coincided with the exit of the cab hailing company's co-founders Raghunandan G and Aprameya Radhakrishna. Post the acquisition, TFS was merged with Ola.
Before becoming CEO, Singhal was TFS' COO for about six months. Prior to TFS, he served as director-south at McDonald's India, Singhal's LinkedIn profile shows. Singhal has also worked with Reliance Communications and Nokia.
BlueStone offers a range of jewellery under five categories, including earrings, rings, pendants, bangles and bracelets. The firm, which used to source merchandise from third-party manufacturers, also manufactures products on its own now.
Last September, Ratan Tata, chairman emeritus of Tata Sons, made a personal investment in BlueStone. This was one of Tata's earlier investments in the technology space. He has become one of India's top angel investors this year.
BlueStone recently raised $16 million in a fresh round of funding led by IvyCap Ventures and Dragoneer. Existing investors Accel Partners, Kalaari Capital and Saama Capital also put money in this round.
In a recent interview with Techcircle.in, Kushwaha said that Bluestone will clock GMV run rate of Rs 200-250 crore ($30-37 million) by the end of fiscal 2015-16.
Bluestone mainly competes with Caratlane, Velvetcase and Karatcase.in besides the horizontal e-commerce players Amazon, Flipkart and Snapdeal in the jewellery e-tailing space.
Institutional brokerage firm CLSA Asia Pacific Markets predicts that the global e-commerce market for online jewellery would grow to $22 billion by 2018.