When looking for a good quality pearl brooch for your wedding, pay special attention to the following:

 The nacre:  this should be even and thick, if you can see the centre of the pearl then that would be a bad choice. 
       The pearls should be smooth but slightly gritty when rubbed in between your teeth. If they are totally smooth then 
       these may be plastic, glass or painted on (sprayed) pearls which are fake pearls.

       Look for pearls with a high lustre & clean surface, which will ensure they sparkle in the light.

 Stringing: Your pearl brooche should be strung with high quality string & a knot tied between each pearl to 
       prevent them rubbing together & wearing the pearl nacre down, which would of course ruin the pearl brooche..

 Colour:  traditionally this has been white to go with a white wedding dress, however you can choose whatever colour 
       you like but make sure the pearl brooche matches the colour of your dress or outfit. 

 Clasps:  these vary from nickle plated metals to Silver & Gold metals.

       Nickle plated clasps: these clasps are very shiny, have superior wear plus corrosion resistance & as a result they 
       make a good choice when you don't want to spend too much money.

       Silver plated clasps: normally these are rated as 925 silver & will be stamped or laser marked with the assayers stamp
       plus our own to ensure that the required amount of precious metal under UK law is present. If items are descibed as 925
       silver then they must have a hallmark.

       Gold plated clasps: these clasps have to meet the same standards as Silver but of course in relation to gold & will
       typically be rated 9k or 18k & hallmarked

Note: the above, applies to all pearl jewellery & that includes a pearl brooche.

As you would expect, gold & silver are more expensive than nickle plated metals, however the choice is entirely your own as 
to which you prefer.