Well, at the great risk of taking on others:
The item you are asking about does seem to be an item from Africa,more or less, but originaly from England, namely a bracelet, an item of personal adornment designed and intended to be worn about the wrist of a female, not about the ankle.
These items were quite popular in the "slave trade" era, from the 17th through the 19th century, along with mirrors, colored glass beads, cotton clothes, cheap guns and so forth.
As for being a "slave shackle", well perhaps so, but no more so than a popo manila.
And if you don't know what a "popo manila" is, then you need to go look it up; there are those on eBay who are selling those as authentic "slave shackles" as well.
Franklin
