Is this eBay Cisco SFP-10G-SR genuine? Checking markings and serial format

The poster bought a Cisco SFP-10G-SR on eBay (markings suggesting 2007 manufacture) and, warned about counterfeit Cisco optics with longevity and safety risks, asked how to tell whether it was genuine before deploying it. Hardware involved: Cisco SFP-10G-SR. Reported symptoms/messages: authenticity doubt; used optics from marketplace.

• Transceivers: Cisco SFP-10G-SR
• Form factor: SFP+

Symptoms / messages:

authenticity doubt
used optics from marketplace