
It's about ninetenths as heavy as a Tennis Ball.
In other words, 260 carats is 0.925 times the weight of a Tennis Ball, and the weight of a Tennis Ball is 1.08 times that amount.
(ITF Standard; for Type 2 ball)Per International Tennis Federation standard, regulation tennis balls must weigh about 281 carats. Competition balls are also tested for bounce height, with the standards requiring that a ball dropped from 254 cm must bounce back to a height of 135 cm to 147 cm.
It's about oneandonefifth times as heavy as a Golf Ball.
In other words, 260 carats is 1.162 times the weight of a Golf Ball, and the weight of a Golf Ball is 0.8606 times that amount.
(per R&A USGA Rules of Golf; maximum rule weight)
It's about fourfifths as heavy as a Battery (C).
In other words, 260 carats is 0.82 times the weight of a Battery (C), and the weight of a Battery (C) is 1.2 times that amount.
(Alkaline)
It's about oneandthreefifths times as heavy as a Light Bulb.
In other words, the weight of a Light Bulb is 0.63 times 260 carats.
(a.k.a. lamp) (for A19size, 60w, incandescent bulb by Bulbrite; package weight)
It's about threefifths as heavy as a Deck of Cards.
In other words, 260 carats is 0.57 times the weight of a Deck of Cards, and the weight of a Deck of Cards is 1.8 times that amount.
(ISO 216 B8 size, a.k.a. "poker size" 63 x 88 mm, 52card deck)
It's about two times as heavy as a Battery (AA).
In other words, 260 carats is 2.2 times the weight of a Battery (AA), and the weight of a Battery (AA) is 0.45 times that amount.
(Alkaline)
It's about twoandahalf times as heavy as a Mouse.
In other words, the weight of a Mouse is 0.4 times 260 carats.
(a.k.a. "House mouse", Mus musculus) (adult) 
