There is a stunning porphyry bowl with a circumference of 15m in the Vatican Museums

Of course, there are no details about how it was made.

Why am I interested in production details? Because the masters' records of the difficulties in processing this most durable material show that it took a month to cut through a small detail on a porphyry medallion, how long did it take to create and polish the bowl?

Why is there no data, how and who created it?