According to Simon Jones for the MailOnline, the club's technical director, Michael Emenalo, watched the teenager in action last week in the club's 1-0 win over Dinamo Bucharest.
Coman is a left-winger and joined Steaua from Viitorul Constanta in August for £2 million.
Per Jones, the Romanian side have inserted a huge release clause in the teenager's contract because "they regard him to be at the same level as Kylian Mbappe."
Mbappe left Monaco for Paris Saint-Germain last summer on a season-long loan, with an option to buy.
The deal could cost PSG €180 million plus bonuses, per Jonathan Johnson at ESPN FC.
Football journalist Emanuel Rosu has said that Steaua owner Gigi Becali believes Coman is even better than Mbappe:
However, Antonio Conte's side are unlikely to want to spend £88 million on a 19-year-old who is yet to establish himself in a major European league.
Yet the club are well-known for bringing in young players and then allowing them to develop elsewhere on loan.
The Blues currently have a whole host of young stars out on loan, as can be seen via the club's official website.
Chelsea could also be keeping tabs on Coman as a potential replacement for Eden Hazard, should he opt to leave Stamford Bridge in the future.
Per Matt Law at The Telegraph, Hazard's current deal expires in 2020, and Chelsea want the Belgian to sign a contraction extension worth £300,000 a week.
After missing the start of the season due to a fractured ankle picked up on international duty, Hazard has quickly returned to his best form for the Blues.
The 26-year-old put in a superb performance in the midweek 2017/18 UEFA Champions League win at Atletico Madrid, as highlighted by Squawka:
When Hazard is playing at the peak of his powers, he has the ability to rival any player in the world, according to sports writer Jake Cohen:
Whether Real Madrid will make a move for Hazard remains to be seen, but in the meantime, Chelsea will hope to convince the Belgian to sign a new contract and commit his future to the Blues.