Which one of the following foreign travellers elaborately discussed about diamonds and diamond mines of India ?

Says Bernier's Travels are 'marked by detailed observations, critical insights and reflection', indicating he tended to describe economic and material aspects of Mughal India in depth.

A student could use this rule (Bernier records detailed material observations) and check whether his itinerary or chapters cover diamond-producing regions or trade topics to assess if he discussed diamonds elaborately.

Notes Bernier observed 'vast quantities of the world's precious metals flowed into India' and mentioned a prosperous merchant community engaged in long‑distance exchange.

Combine this with basic knowledge that precious stones were part of long‑distance trade to evaluate whether Bernier likely commented on gemstones (including diamonds) and trade/mine locations.

Bernier praised Indian workmanship in 'beautiful gold ornaments' and fine metalwork, showing attention to precious goods and their manufacture.

Given his interest in jewelry and luxury goods, a student could plausibly search his text for extended treatment of gemstones/diamond sources to see if he discusses mines or gems at length.

Gives publication and circulation details of Bernier's works (widely translated and reprinted), implying his accounts were comprehensive and accessible to contemporaries.

A student could use this to justify consulting the published editions/translations (mentioned here) to directly check for extended chapters or passages on diamonds/mines.

Mentions diamonds were exported from Pulicat, indicating active diamond trade centers in the region during the period, a subject a detailed traveller might report on.

Using knowledge of trade ports, a student could map Bernier's travel route against known diamond export centers to infer whether he had opportunity to observe/describe diamonds or mining activities.