It is well known that finding an accurate forecast of future volatility turns out to be very useful for pricing derivatives, hedging strategies or for the calculation of the Value at Risk. The market's assessment of the underlying asset's volatility as reflected in the option price is known as the implied volatility of the option. Based on teaching derived from these recent papers written on the forecasting ability of implied volatility, this paper deals with the accuracy of international volatility indexes (VX1, VDAX and VIX). First, we find that VX1, VIX and VDAX are good tools for predicting future realized volatility and we also show that past implied volatility informs more about future implied volatility than past realized volatility. We, also, embed each of the implied volatility indexes as an exogenous term in the GARCH variance equation and find that all of them dominates the GARCH terms. Second, We also compute parameters of a stochastic volatility model using implied volatility indexes. Third, we study the transmission mechanisms of implied volatility indexes.