What does ハンマー look like on HTC?

On HTC it is the design shipped in Sense 8, shown above at full size. Older revisions are listed beneath it.

When did HTC add ハンマー?

HTC first drew ハンマー in Sense 7, released 2015年3月30日.

HTC Corporation has shipped 2 versions of ハンマー. Each is dated, so you can see when the design changed.

HTC

HTC Corporation has drawn ハンマー 2 times. Every revision HTC has shipped is below, newest first.

What does ハンマー look like on HTC?: On HTC it is the design shipped in Sense 8, shown above at full size. Older revisions are listed beneath it.
When did HTC add ハンマー?: HTC first drew ハンマー in Sense 7, released 2015年3月30日.
How many times has HTC redrawn ハンマー?: HTC Corporation has shipped 2 versions of ハンマー. Each is dated, so you can see when the design changed.

HTC artwork for this emoji spans 2015 to 2016.