I was going to create a wizard with the sailor background. Now the Sailor starting equipment in the PHB states that I get a lucky charm. Either a rabbit foot, small stone with a hole in it, or something from the trinkets table. I rolled a gemstone that looks like coal when inspected by someone else other than me. Also to mention that this gemstone does not specify a price.
Could this gemstone be a diamond?
Can I use this to cast chromatic orb?
The rules are silent on the value of trinkets, but sure... it could be a diamond.
The diamond required for Chromatic Orb has a minimum value requirement. Allowing a freebie "trinket" to count as something worth 50 GP drastically increases the character's starting resources.
DDAL tracks treasure awarded and treasure spent. If you didn't log recieving the cash and didn't log spending the cash, you don't have the object.
The prestidigitation spell can create "nonmagical trinkets" which last until the end of your next turn. That's long enough that you could, say, conjure a jade circlet and then use it to cast shapechange for free instead of spending 1500 gp. That's clearly not how spell components are intended to work.
Rules as intended, I do not believe trinkets are supposed to have any mechanical value.
As a DM, I would let the trinket be made of whatever you want, but I would not let you use it for anything other than role playing and I would not let you sell it for more than a few copper.
Unless your DM tells you otherwise.
The cost of the components is for balancing so you can't ignore them without consequences.
