Capital gain tax on selling of gold

According to Me, your mother has to file ITR for AY 13-14. Capital Gain Computation will be: Full value of consideration (Selling Price)Rs.660000 Less: Transfer Expenses NIL Net Consideration [A] Rs. 660000 Less:Indexed Cost of acquisition [B] Cost of purchase X 852/223 = XXXXX (in your case cost of previous owner ie. your grandmother)(here i assumed indexation of purchase 1992-93) Taxable Long Term Capital gain will be [A-B]

ganeshan is right....

please advice how I would get the purchasing cost of previous owner (My Grandmother). My mother dont have any receipt from my grandmother. then how much cost of purchase will be assumed. and how much capital tax wil be come.

AS PER MY OPINION IT SHOULD BE THE GOLD RATE PREVAILING IN THE IN THE YEAR IN WHICH GOLD PURCHASED.

Mr Ganeshan is right

Cost of acquistion will be taken as the same Cost of acquistion of previous owner (i.e in this case her mother in law)

However, in such a case if the actual date of purchase /or receipt is not available neither is stamped on the jwellery then it is advisable to take the rate of gold prevailing in the year of her marraige and index accordingly... 

I believe discussion above has answered first part of your question.

I would like to answer second part :

As per Section 112 of IT Act, 1961 if in case of a resident individual,  the total income is lower than maximum exemption limit then the amount of shortfall will be covered by Long Term Capital Gains. It means that whatever Capital Gains you compute will go on to be adjusted with the amount of shortfall of the other income of your mother till the limit of Total Income which is Rs 2 lacs is reached.

Hope it may b sufficient for the second part....