With solid fundamentals backing the current move in GLAS, this could just be the early phase of the uptrend. The AVWAP from the current highs is around Rs 21.10 - Buyers need to keep an eye on this level. Closing above this on high volume would likely put the buyers back in control and initiate a strong upside move.
Right now, the stock is trading above a rising 50 and 200 day MA meaning that both the medium and long term trend is very much favoring the buyers.