Not India specific, but generally for a VC investment, atleast one of the investors in the round needs to lead the series (determine pricing) and go through the basic diligence steps (verify real prototypes, right team etc etc). If they have a lead investor lined up and they are looking more money to finish up the raise, I'd say it's worthwhile to consider. If it's pre-product, your making a big bet into the management team and the story, so I'd focus there. If you're a lone angel / seed investor, there's no lead investor, and you're too far to do the diligence ... that would be an easy pass in my book.