If anything
Quote from John gruber Twitter "Emoji arent accepted characters for the Color watch face monogram, but regular Unicode glyphs are."

https://mobile.twitter.com/gruber/status/589510016799006720/photo/1
https://mobile.twitter.com/gruber/status/589510016799006720
And from 9to5mac
"There are several different other aspects to the information that the publication received, including the ability to imprint a digital monogram on certain clock faces. This means that the wearer can put a series of letters, up to four it seems, and imprint them on a certain clock face to give it that bit more of individuality."
Quote from John gruber Twitter "Emoji arent accepted characters for the Color watch face monogram, but regular Unicode glyphs are."

https://mobile.twitter.com/gruber/status/589510016799006720/photo/1
https://mobile.twitter.com/gruber/status/589510016799006720
And from 9to5mac
"There are several different other aspects to the information that the publication received, including the ability to imprint a digital monogram on certain clock faces. This means that the wearer can put a series of letters, up to four it seems, and imprint them on a certain clock face to give it that bit more of individuality."