VINTAGE BLACK VELVET SKIRT XS ST. MICHAELS PENCIL SKIRT LINED HOLIDAY

I have for sale this gorgeous vintage/retro St. Michael’s black velvet pencil skirt. It has a zipper up the back and a closure. It is marked a size 10 but when I went to put it on the mannequin, it was clear it was much smaller than that because I couldn’t fasten in the top hook on the skirt when it was on the mannequin.  I believe this to be an extra small according to a size conversion chart I found online. I have attached a picture of that chart as well. The measurements of the skirt are as follows: 25” waist 33” hip 25.5” length 5” back slit