The tournament ring a not even half powered Toguro lifted.
Calc 1:
It looks like it's 30-ish meters in diameter and ~1 and 1\2-ish meters thick in that shot. So r=15 and h=1.5
Volume of a Cylinder\Disk = ([pi][r]^2)*[h]
So, ~3.14 * 15^2 * 1.5... that equals... 1,059.75m^3
The density of Granite is 2,600[?]kg per cubic meter (Just an assumption that it's granite; it's impossible to say for sure I think.)
So this comes out as 2,755,350kg.
Converting this, this becomes 2,755.35 metric tons...?
A low-end calucation would be ~18 tiles across with each one being 1 or 2 meters (depending on the scene.) So 18 meters across. And the ring is as thin as a third of a meter depending on the scene so...
~3.14 * 9^2 * 1\3... that equals... 84.78m^3
84.78m^3 * 2,600kg\m^3 = 220,258kg. So around 220.258 tons
Calc 2:
Granite weighs 2600 kg a meter cubed. Although the size isn't consistent, it generally hovers around a little over 10 m diameter and a little under 1 m thick. This means it probably weighs between 200 and 225 tons