Where can I see how Emojis will appear on different devices?

Emojis will appear differently depending on the device or OS that device is using. Here is a resource that will display for you how an emoji will appear on all devices/operating systems.

We also highly suggest that you test the content in which you are placing the emoji. For example, if you are placing the emoji within an email, you should test viewing the emoji within the email on multiple devices.