No ruby bearing there. That is likely congealed lubricant coating the tip of the rotor post. The post itself is tempered steel, and the rotor has what is often called a rotor bearing gear friction fit in the middle of the rotor. Beneath the rotor is the gear that drives the self wind gearing. The bearing gear is separate from the rotor, and is a friction fit which allows the bearing gear to be removed and replaced. The bearing gear is a precise fit over the rotor post, and the rotor turns on that post. No jewel there, sorry!
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