silk vest with suit

All -

Is it a fashion faux pas to wear silk vest with suit? How about a tux
vest with a suit? Let's assume that its a dark (black, navy blue)
suit.

Xopher...

You wear tux vest with a tux. You will end up looking liek you could not
dress in either suit so you decied to try them both at once. The upscale
bag man is not a good look. For God's sake do not wear a silk vest with
wool suit. Here is generalization on what to wear and when:

WHAT TO WEAR ON VARIOUS OCCASIONS

The appropriate clothes for various occasions are given below. If ever in
doubt what to wear, the best rule is to err on the side of informality.
Thus, if you are not sure whether to put on your dress suit or your Tuxedo,
wear the latter.

FULL DRESS
1.. At the opera.
2.. At an evening wedding.
3.. At a dinner to which the invitations are worded in the third person.
4.. At a ball, or formal evening entertainment.
5.. At certain State functions on the Continent of Europe in broad
daylight.

TUXEDO
1.. At the theater.
2.. At most dinners.
3.. At informal parties.
4.. Dining at home.
5.. Dining in a restaurant.

A CUTAWAY OR FROCK COAT WITH STRIPED TROUSERS
1.. At a noon or afternoon wedding.
2.. On Sunday for church (in the city).
3.. At any formal daytime function.
4.. In England to business.
5.. As usher at a wedding.
6.. As pall-bearer.

BUSINESS SUITS
1.. All informal daytime occasions.
2.. Traveling.
3.. The coat of a blue suit with white flannel or duck trousers for a
lunch, or to church, in the country.
4.. A blue or black sack suit will do in place of a cutaway at a wedding,
but not if you are the groom or an usher.

COUNTRY CLOTHS
1.. Only in the country.

To wear odd tweed coats and flannel trousers in town is not only
inappropriate, but bad taste.