To start this page off; Mostly the water/earth elements are responsible for jewelry.
These angels are specifically trained, to create seals, that entrap a soul, if corrupted or not. They use the reflections of light inside jewelry, to entrap them constantly. Since demons are sensitive to bright lights, they are stuck permanently, unless freed. The multiple relections, create a strong light, where they get sealed at the center of the gem. If a demon is trapped, they turn basically to statues, worst-case scenario, could die, if the densite of the gem is that of the diamond, aquamarine, or other gems, that have a very light color or are clear. (which are difficult to create.).
Depending on color, is the strength of the seal. Earth-element angels tend to create stronger gems, though take longer to create.
Warm colors
Brown
Coral/shrimp-ish pinks
Deep Red
Red
Orange
Amber
Yellow
Lime-greens
Cold colors
Cold/Forest-greens
Blue
Deep Blue
Purple/Fuchsia
Hot Pinks or mixes
Clearer gems/minerals/crystals
Aquamarine
Clear Quartz
Milky Quartz
Rose Quartz in the lighter scales
Pearls
A demon is only freed, once the jewelry is destroyed. For that reason, angels take on keeping them safe in their massive archive. If a demon is willing to cooperate, they tend to talk to them sometimes.
If you shatter a gem or crack it in rapid succession, it can cause a demon to "leak." If so happens, the angel can be infected, by its leaking blood, since the light weakens their bodies and injures the trapped demon in question, causing their infectious blood to leak through the cracks. They have a nickname of "demon's shattered heart", which is why they warn every angel, dealing with gems, about its info. If the cracks are too severe, a demon can break free, by destroying the gem, from the inside of their confinement.
A few angels tend to have jewelry on them, in case multiple incidents tend to occur, where they encounter demons or their energy is depleted more often. If you are under suspicion, you will be surveillanced by higher-ups of the corresponding angel. If your incidents happen so often, or are so severe they deserve the attention of a tutor/they alarm others, they will be given jewelry, in their choice of shape to prevent injury-traumas from reoccuring. (read about it in the folder, in case not familiar with the term)
Other reasons than demons, would be the protectors passing them on;
If an angel passes the protected divinely-crafted jewelry on, said jewelry will protect their target further, not the angel. Although, if the mineral encased in metal breaks, the angel will be immediately alerted by senses naturally in them, to investigate why it shattered; Often times, that instinct saves the protected from being attacked any further successfully. It's used for angels, who still train their death-senses.