Yes. Tinting, adding pearls, and adding metal flake to DiamondFinish Clear is extremely common.
DiamondFinish Clear is a moisture-cured urethane, so anything added to it must be 100% dry and contain no moisture. Moisture contamination can interfere with curing and negatively affect the final finish.
In general, compatible additives include tints, candy tints, pearls, and metal flakes that are specifically designed for use with urethane coatings. These are commonly available at most automotive paint and body supply shops.
Tip: Only mix the amount needed for a single application session. Once tints, pearls, or flakes are added, the pot life of DiamondFinish Clear may be reduced.
DiamondFinish Clear Application Directions: https://www.kbs-coatings.com/diamondfinish-clear-directions