Are you breaking the rules? Matching your watch with your attire.
First things first, match your watch to the formality of your dress code, then consider the following.
Leather should complement leather
Ideally the material and color of your shoes should dictate all your other dress accessories. Starting point should be matching your belt with your shoes and then your watch with both.
Traditionally for women, the starting point likewise would be to match the shoes with the bag and the belt if there is one and then to the watch.
A black pair of shoes, with a black belt. If the choice is to wear a leather band watch then this should be worn with a black leather band watch. If the choice is brown, then all three likewise should match.
With brown and other colors, the tones do not necessarily have to be the same. A watch with a leather band in a lighter shade of brown can be worn on a darker shade of brown shoes. As much as possible, avoid the tones being too far off.
Metal Should Complement Metal
When talking metals on a wristwatch, it is important to distinguish between the watch case and the watch band. The watch band is the watch while the watch case is the adornment. This is why you hear people describe a watch by the band and not the case. So the watch band is like the belt while the watch case is the buckle.
The watch case should therefore be matched with the adornments of your other accessories while the watch band should be matched with the accessory itself and your clothes.
The watch case: Except for your wedding band, all the metal accessories in your attire should complement one another. The buckle or metal adornments on your shoes, the buckle of your belt, your cufflinks, and so on should all be the same color.
Like with the leather bands, though the colors are to be the same, the tone do not necessarily have to match. So when doing gold for instance, you can match shoes with yellow gold adornments with a wristwatch with a rose gold case. Likewise, a pair of shoes with a black buckle can be matched with a wristwatch with a gun metal case.
The watch band: Metal bands generally are more versatile than leather bands. So, unlike pairing a pair of black shoes and a wristwatch with a brown leather strap which is an absolute no; there are no absolute dos and don’ts with the metal bands.
Certain colors however are a better paired with some colors. Silver band watches go better with black, grey and the darker shades of blue. Gold watches on the other hand go better with brown, tans, beige and other earth colors.
In an era where colors are fashionable and we have watches coming in blue, red, green, yellow bands and so on, matching the color of your watch to those of your shoes could pose a bit of a challenge especially for men. In cases like these, some level of discretion would need to be applied, but a safe bet is always a black pair of shoes preferably with no buckle/adornments.
Watch your Cuff
When wearing a long-sleeved shirt, the cuff of your shirt should naturally slide down your wrist and cover most or all of your wristwatch without needing any assistance. This is not negotiable especially when dressing formally and it is the main reason why the classic formal watch is a leather strap watch with a slim case.
This is not to say that metal band watches with slim cases cannot be worn formally. Unlike the leather bands, the bulk of the metal bands (in some cases) could become an issue especially when the shirt requires the use of cufflinks. So, if you must wear a metal band, make sure that the band isn’t so bulky that it bulges or pushes on your cuff.
Whatever you do, do not wear a watch so bulky that not only can your cuff not cover it, you have to pull up your sleeve so it rests just before your watch or worse still wear the watch on the sleeve of your shirt.
The above is the traditional perspective to things. Fashion however changes from season to season. What was right in 2010 might become a fashion faux pas in 2020. The traditional perspective however is always in vogue.