(Above) 10.54ct e998 Turquoise on a 5 cent coin (coin measures 16.8mm)
(Above) 11.18ct e110 Turquoise on a 5 cent coin (coin measures 16.8mm)
Although the 11.18ct turquoise is heavier than the 10.54ct. In terms of size, the 11.18ct looks smaller than the 10.54ct due to a higher dome.
Colour, the 11.18ct has an intense turquoise colour, the 10.54ct has a light turquoise colour, slightly lighter than the corporate blue colour of https://www.tiffany.com/
Clarity, both turquoise are opaque
Cut, the 11.18ct turquoise has a high dome, the 10.54ct has a medium dome and a bigger face.
If you are concerned that the stone look to big, I would suggest the 11.18ct e110 Turquoise.