Violet Gem Ring : 2MM 3
It seems you pressed the correct button.
If you remove the common words from the three statements, the conditions become clear.
“A circle and a triangle are lighter than a circle and a square” means the triangle is lighter than the square.
“A circle and a square are heavier than a square and a triangle” means the circle is heavier than the triangle.
“A square and a triangle are lighter than a circle and a triangle” means the square is lighter than the circle.
Therefore, the order from heaviest to lightest is circle, square, and triangle.
The lightest shape is the triangle.
Soon, a part of the wall beneath the buttons opens, and the Violet Ring treasure is revealed.
You take the treasure from the small space inside the opened section of the wall and secure it.
After obtaining the treasure, you leave the area.
You make your way out.
You successfully secure the treasure.
Congratulations!