Unknown Small Magnifying Lens

Description

Unknown Small Magnifying Lens or Jeweler's Loupe. Pre-owned and likely if late 60s to 70s vintage. Ships via Priority Mail small flat rate box.
This item cane to me through my stepmother's family. She's passed on now, so I cannot confirm it's origin. But her mother (my former step-grandmother) was remarried to an geological engineer who worked for an oil company in the 1960s and 70s. The reason I mention this is because this item could have been a loupe used to look at geological samples in the field, or maybe to look at aerial photos when searching for new oil deposits. We just aren't sure.
The one thing we know is that there are no jeweler's in the family, plus we have several of his slide rules from the period. This item was also found in conjunction with an original "Emoskop".
It is 1 3/8" long and has a diameter of just a hair less than an inch. It looks to be machined from one piece of non-ferrous metal.
**Update 6-9-21
Some people who've seen the  item on various forums believe it to be an eyepiece for a telescope. One user mentioned there used to be a size standard that was 0.96" diameter. Now I don't own a set of calipers or a micrometer, but like I said, it is just a touch less than an inch.