Thank you very much for your question. It is our pleasure to answer it.

In the name of Allah, We praise Him, seek His help and ask for His forgiveness. Whoever Allah guides none can misguide, and whoever He allows to fall astray, none can guide them aright.

Dear sister, it is permissible to pray in such clothes, so long as they are pure (tahir) and cover the `awrah (the entire body except the face and hands) women , although it is better and more perfect to wear beautiful clothes that look good for prayer. That is in obedience to the command of the Almighy Allah in the verse (interpretation of the meaning): 

"O Children of Adam! Take your adornment (by wearing your clean clothes), while praying"... (Al-`Araaf 7:31) 

And Allah knows best.