Buffett has been consistent in his praise for Indian- origin Jain, one of the key executives at the investor's sprawling Berkshire Hathway business empire.
Jain, associated with Buffett for nearly three decades, has long been speculated as being a potential candidate to succeed the octogenarian investor at the conglomerate.
"From a standing start in 1985, Ajit has created an insurance business with float of USD 37 billion and a large cumulative underwriting profit, a feat no other insurance CEO has come close to matching.
"Ajit's mind is an idea factory that is always looking for more lines of business he can add to his current assortment," Buffett said in his latest annual letter to shareholders released on Saturday.
Last year too, the maverick investor had praised the business acumen of Jain who holds the reins of Berkshire Hathaway Reinsurance Group.
According to the letter, Berkshire's attractive insurance economics exist only because of some terrific managers running disciplined operations that possess strong, hard-to-replicate business models.
Among the conglomerate's major units, Reinsurance Group is first in terms of float size.
Jain insures risks that no one else has the desire or the capital to take on, Buffett said, adding that he never exposes Berkshire to risks that are inappropriate in relation to the resources.
His operation combines capacity, speed, decisiveness and, most important, brains in a manner unique in the insurance business, Buffett said.
"Indeed, we are far more conservative in avoiding risk than most large insurers. For example, if the insurance industry should experience a USD 250 billion loss from some mega-catastrophe -- a loss about triple anything it has ever experienced -- Berkshire as a whole would likely record a significant profit for the year because of its many streams of earnings," the letter said.
"And we would remain awash in cash, looking for large opportunities if the catastrophe caused markets to go into shock. All other major insurers and reinsurers would meanwhile be far in the red, with some facing insolvency," it added.
In 2013, Berkshire Hathway's gain in net worth was USD 34.2 billion while full-year profit was over USD 19 billion.