Drem yol lok to all! I'm DMing a homebrew Dungeons & Dragons campaign in the next couple months and plan to use Dovahzul as the equivalent of Draconic (the lexicon is so much more robust than anything in the official D&D settings). In my homebrew world I even have a continent ruled by a tenuous balance between metallic, chromatic, and gem dragons. That said, I wanted to pick your brains on certain words. I'll make a list of what I'm focusing on for now and put what I don't have yet in bold. I'd love to hear your input.

Cardinal Directions
North: Brom
West: ???
East: Jer
South: ???

Colors
Red: Sahqo
Blue: Bii
Green: Graag
White: Sot
Black: Ved
Gold: Yuvon
Silver: ???
Bronze: ???
Brass: ???
Copper: ???

Gems
Amethyst: ???
Crystal: ???
Emerald: ???
Sapphire: ???
Topaz: ???

Zu'u saraan hin aak! Kogaan!

 As a general rule they didn't make a word if they didn't need it so we lack many words we might want. Trying to describe something using what we do have is the best alternative.

Vojer and vobrom work for directions.

The others are harder. Colours can sometimes be described by other colours. You could try describing the qualities of the metals in more vague terms like "viin dwiin" for silver (googling the properties of the metals might give you better ideas). Same with the gems. You could assign either of them mythical inworld properties to give yourself flexibility.

Using canon often means getting creative unfortunately.