My bet is that this is not natural spinel. Could be Be sapphire, but I doubt it because even a 5.5 carat VS Be treated sapphire might be hard to get for “cheap”. Of course inexpensive is a realtive term.
Could be (probably is?) synthetic. The only thing that pushes me away from synthetic is the fact that it is only graded as VS, but even some synthetic spinels and corundums have inclusions. Could even be quartz. At any rate, I’d about fall out of my chair if this came back natural spinel.
Please do post the results of your appraisal.