Conway Stewart for identification

[shalitha33]

I'm no Conway Stewart expert, so what I say can be very wrong. Please do correct me.
It's probably best to not wash the inside of the cap (threads) or any internal parts unless its necessary to do so. There is an internal blind cap protecting the cap material from ink up to around the threads, 

 

These are two pens with black / green pattern both identical size. 
 

 

surface magnified to 9X looks as follows for the undamaged pen (with the clip)

for the pen without the clip it looks as follows 

 

There are tiny hairline cracks deep within the material, often only visible under magnification and on light colored areas. They tend to form when pen dries up after getting wet.

some of these minor marks deep within can link up forming a larger crack

Note that this only apply for this black /green pattern. For the other types it can be different such as for this copper blue pattern. Bright blue turns to a blue-gray