Level of Detail

There is no specific standard for the appropriate level of detail across the pack. As a general rule, emojis should be designed as simple as possible while still conveying what they are. The best way to gauge what the level of detail should be is to look at emoji's within the same category as the ones you wish to create. That said, there are some specifics for certain categories. These include:

Expressions

Expressions are a special category within the pack and should be treated slightly differently. They should use softer edges and generally be kept as simple as possible while conveying the emotion.

Animals

Animals should be detailed, sharp, and include many intricacies. The (non-emotive) cat emoji is a great example of this. It contains many details yet is still generally quite simple.