Assuming this person is a US taxpayer (i.e. US citizen or resident filing Form 1040 rather than noncitizen/nonresident filing 1040NR), then they must report and pay tax on all gains worldwide. Since they paid tax on the sale in India, they will likely qualify for the foreign tax credit to negate the double-taxation aspects.

Report the sale as you would any other property, then use Form 1116 to report the gain and tax paid to India to calculate the foreign tax credit.