The pen you are looking at is from Montblanc's famous Boheme line. This pen line is no longer produced by Montblanc and is becoming increasingly rare on the market.
The pen is a ballpoint version with a body made of high-quality black resin from Montblanc. This version has metal details using an elegant red gold plating, perfectly combined with a meticulously filed smoky brown gemstone attached to the clip.
The iconic Montblanc logo is also clearly visible on the top of the pen. The pen is a display version that is currently being heavily discounted.
Details: https://butchinhhang.com/san-pham/but-montblanc-boheme-marron-ballpoint-pen-38270/