Upvote:2
Since you asked for an official source, here's a guide for travelers freely available on the Central Board of Excise and Customs website for the Indian Government. They also happen to have a set of baggage rules complete with appendices which should clarify all the rules.
Regarding your specific questions and just for the sake of providing a short summary of the detail inside the document,
Used personal effects (excluding jewellery) required for satisfying the daily necessities of life - Free
Other articles carried in person or accompanied in baggage - Rs. 35000 if the stay is greater than 3 days
One laptop computer (notebook computer) is allowed duty free if imported by any passenger of the age of 18 years and above
Alcoholic liquors or wine up to 2 liters and Tobacco up to 200 cigarettes or 50 cigars etc.
They are not very clear in the document regarding jewelry but as far as I understand, if you are carrying jewelry on your person and not in any sort of baggage (i.e. you are wearing it) you wont be liable to declare it, otherwise you will be.
Do read the document for an accurate insight into what is correct and valid.