Factors taken into account by the Unicode Consortium when deciding which new emoji to accept as candidates include:
- Proven past use of a symbol in prior text or communications
- Popularity / likelihood an emoji will be frequently used, if introduced
- Gaps in groups of emoji, such as sports
- Compatibility with emoticons and pictographs used in other instant messaging or email platforms.
2014 has been a big year for emoji, with a wide range of new emoji introduced in Unicode 7.0 (unfortunately with no implementation from the major platforms yet), support for nearly all country flags in Android 5.0, as well as the proposal for racially diverse emoji.
Unicode 8.0 is scheduled for release in mid-2015.