COD mobile has given the players a lot of free weapon skins in the form of camos. Each and every weapon has these skins which is really cool. Some of them are much cooler than the others which is the completionist camos for all the weapons. This category has 4 skins which are the max level skins for a gun. They are the gold skin, platinum skin, Damascus skin and the diamond skin.
Free Gold Skin
For this skin you will have to complete the challenges for that weapon to unlock the gold skin. You will have to complete challenges like killing 100 enemies wiht headshots, or killing a certain number of enemies with hip fire or killing a certain number of enemies with 0/5 attachments etc. Once you complete these challenges then you will unlock the gold camo.
Free Platinum skin
This skin for a weapon will be unlocked when you unlock all gold camos for that weapon category. for example you will need to unlock the gold camo for all the assault rifles to unlock the platinum skin for that weapon.
Free Damascus Skin
This Skin is the second most max level skin for a weapon. To unlock this weapon skin you will have to grind a lot in the game. You will need to unlock the gold camo for all the weapons inside the game to get this skin. For example to unlock Damascus camo for DRH then you will first have to unlock the gold camo for all the assaults' rifles, SMGs, LMGs, Sniper Rifles, Launchers etc. This is the hardest skin to unlock in the game and is often referred to as Road To Damascus.
Free Diamond Skin
This diamond skin was recently added to the game and the only way to unlock this skin is by first unlocking the gold camo for a particular weapon and then killing 10 enemies in a single match 150 times. You will have to kill only 10 enemies in every match. If you get, lets sat, 20 kills in a single match only the first 10 kills will be counted. So basically you will have to play 150 matches to unlock this skin. This diamond camo is by far the best grindable camo in the game.