It’s not a very important question, but it’s important for me. I’m using the Gmail chat with friend and with colleagues and when I write an heart it’s doing that: 
And when my colleagues make an heart too with the same bind ( <3 ) it’s doing that: 
Why it’s not the same?
And how I can do the big heart with gmail chat?
Thank you in advance for your answers.
You can use different emoticons. Click on the smile on the right bottom side of the input box, and change your emoticons..