As the water exerts upthrust on the stone, the stone also exerts the same force on water, according to Newton's third law. 

Upthrust force acting on the stone is

$\begin{array}{c}U=V_{\text{stone }}{\rho }_{\omega }g\\ =\left(\frac{m_{\text{stone }}}{{\rho }_{\text{stone }}}\right){\rho }_{\omega }g=\frac{0.5}{{10}^4}\times 1000\times 10=0.5\mathrm{N}\end{array}$

Also, the weight is exerted on the beaker. Therefore the reading will be 1.5 + 0.5 = 2kg.