How many times is diamond harder than sapphire?

You can see in the link, below, that a diamond is ranked as 10 on the Mohs scale of hardness, while a sapphire is ranked as 9. The Mohs scale ranks the hardness of minerals.

The Mohs scale is an ordinal scale, meaning -- from Wikipedia:

"Rank-ordering data simply puts the data on an ordinal scale. Ordinal measurements describe order, but not relative size or degree of difference between the items measured. "