Originally Posted by JamesBill
I really appreciate your advice but I would say you are a bit over the top on the "Business Attire" definition. Dress has slid to the casual. My office and all the companies I deal with are either business casual or business. I rarely see suits outside of higher management. Tech has irrevocably changed dress in this country in all offices even outside of tech.
But back on topic, I love ties and have many I don't often wear because I don't wear them without a jacket. Most of the blazers I see are worn without one so I was just asking. I prefer to show off a tie. Why no black trousers though? I was thinking of this or something similar, and most have black trousers. http://img.photobucket.com/albums/v415/FredM/blazer_zps4e41d2bc.jpg
Sure. There are places with more lax interpretations and a smaller number of people who follow the rules, but the most traditional definition still means suit and tie. I don't think you'll ever go wrong wearing a suit and tie to something that calls for business attire, while you could go wrong dressing below this level of formality. Since you mentioned that most people would be in a suit, I kind of assumed that a suit would be expected. I still say you should get a suit / wear a suit, but it is ultimately your call.
As for the jacket, it appears to be an orphaned suit jacket. Blazers and odd jackets (jackets not to be worn with matching trousers) tend to have various features (texture, pattern, patch pockets, buttons that don't match the coat, etc.) that differentiate them from suit jackets. As for the jacket itself, grey is not very versatile compared with navy. There's a strong preference on here for medium grey odd trousers instead of navy for a number of reasons (another can of worms, there are threads), so navy ends up being a smarter choice. I'd get a navy blazer (if you can't stand metal buttons, do something like brown horn, mother of pearl, etc.).
I am guessing they paired the jacket with black trousers in that photo because of a limited number of good options. Black trousers are pretty useless IMO; black is generally not recommended for daytime as it is a bit severe (blue and grey are much preferred), and is too formal a color to work well with an odd jacket / odd trousers ensemble in the evening, where black could be more appropriate. Cream linen or flannel trousers can look lovely with a navy blazer, but since you are going with a business attire look, medium grey would be far better.