Ethnic wear at work has gone from exception to routine across a lot of Indian offices. The technology sector led it, and ethnic Fridays in Chennai and Bengaluru quietly became ethnic Tuesdays and Wednesdays too. Even in the more conservative professions, law, finance, medicine, the man who wears Indian dress well is now read as deliberate rather than underdressed. What separates ethnic wear that reads as professional from ethnic wear that reads as weekend clothes is the same thing it always was: cloth, fit, and whether the garment was chosen for the room it's being worn in.
What actually works at work: the garments and the standards
The bandhgala in a good suiting cloth is the least ambiguous of the lot. Charcoal, navy or black worsted over a fine churidar or a formal trouser is formal in any Indian office, full stop. The kurta moves depending on cloth and context: a fine handloom cotton or a Chanderi is smart-casual almost anywhere, a silk kurta reads semi-formal, and neither one substitutes for proper business dress in the most conservative firms. Know which building you're in.
The Nehru jacket is the Indian smart-casual blazer. Over a plain shirt or a fine kurta, it lifts casual to smart-casual and smart-casual to semi-formal without any effort on your part. In fine silk or a textured cotton it's probably the most useful single piece for a man who wants to keep an Indian look while covering everything from a casual Friday to a client meeting.
The quality signals your colleagues notice, whether or not they say so
The signals are the same as in Western workwear: fit, cloth and condition. A kurta that's too wide, too long or simply the wrong size reads as casual whatever it's made of and whatever it cost. A fine handloom cotton kurta that fits properly reads as carefully as a good business shirt. Keep it clean and pressed. A crumpled or faded kurta costs you more standing than a crumpled shirt would, because ethnic wear at work is still being judged example by example, and yours is one of the examples people go by.