Are Lindsay Lohan and Samantha Ronson engaged?

Is that an engagement ring on Lindsay Lohan’s finger?

That’s the rumor going around on all the celebrity gossip blogs this morning after Lindsay was spotted checking in at London’s Heathrow airport with Sam on Monday, wearing a huge diamond ring on her right hand. The pair then proceded to the airport’s first class lounge, holding hands.

After landing in L.A., Lindsay was also potographed letting herself into Sam’s house while the DJ shopped around for a new Porsche.

While in London, Lindsay also wrote the following on her twitter page:

“Leaving London but with my favourite favourite!!!-travel buddy & great news to share!! Maybe…. ;)”

So this great news she tweeted about – Are Lindsay Lohan and Samantha Ronson engaged?