Diatoms are one of the most important and abundant sea organisms or universal photosynthetic eukaryotes mainly found in water sources. Diatoms are also called as ‘jewels of the sea’ or living opals because of their visual properties. Till now there are more than 16000+ diatoms present but still, some are not identified or unknown yet. The size of diatoms is generally 2–200 µm. Diatoms come under various shapes i.e. square, cylindrical, rounded, cubical, zig-zag, rhombic, etc., their shape is not fixed. It is characterized by its hard but porous outer wall which is of silica, the silica wall is transparent in color. This paper will delve into an in-depth exploration of diatoms and their varied characteristics. Additionally, we will investigate the potential discovery of new, undiscovered species, examining their classification and distinctive features by compound microscope. Furthermore, the study will explore the chemical tests employed for separating diatoms from water.