Q: Our bathroom was renovated in late 2015. We installed a quartz vanity countertop, I think Caesarstone. When it was new, it was fairly shiny — not a full gloss finish, but the equivalent of a semi-gloss. It has dulled considerably. Any easy fixes?

A: So-called quartz countertops are manufactured in factories. A mixture of natural quartz particles, pigments and polymer resin is poured into a mold, compacted, vibrated, baked and given a surface finish. So when you are cleaning one of these countertops or trying to restore a finish, you’re dealing with two different components: bits of quartz, and the tough plastic material around them.

Sometimes when a Caesarstone countertop looks dull, it just needs careful cleaning, said Ruthie Batson, who works on warranty and technical services issues for Caesarstone. She recommended using Soft Scrub’s gel cleaner that contains bleach, but not abrasives, which she said are important to avoid.

Sharon Miller, senior learning and business development specialist for Caesarstone, also recommended the Soft Scrub Gel cleaner with bleach, but she said that when there is “built-up patina” that makes the surface look dull, it’s a good idea to use Bar Keepers Friend Cleanser, in powder form, with the gel cleaner.

“Begin by pouring a small pile of powder in the center of paper towel,” she said. “Pour the Soft Scrub Gel directly over and mix the two together until toothpaste-like consistency. Gently rub in a circular motion (like waxing a car) about 4 square feet of surface at a time. Gently rub the affected area for no more than one minute.” She emphasized “no more than one minute” and added that you should use light hand pressure. Immediately rinse off the cleaner and residue with water and dry the surface with a clean paper towel. “If you see a darker color coming off onto the paper towel, it is working,” she said.

If that doesn’t restore the shine, you’re probably out of luck on finding an easy fix, Batson said. Caesarstone offers four surface options: honed, concrete, rough and polished. Polished is actually semi-gloss, the finish you describe. A polished finish “cannot be repolished in the home,” Batson said. She said the countertop would need to be removed and taken to a shop where a countertop expert with special equipment could use a series of progressively finer abrasives to restore the original look.

When some natural stone surfaces get scratched up and look dull, it’s possible to sand them with very fine abrasives to give the surface an even look, which generally is better than one that is dull or scratched up in only some areas. That is an option with quartz countertops, Batson said — but not one Caesarstone endorses.

Caesarstone and other manufacturers tout their materials as stain-resistant and easy to care for, but incorrect and abrasive cleaners can dull the surface. Even Simple Green cleaners can dull the surface, Batson said.

The Caesarstone website recommends cleaning with Soft Scrub Liquid Gel, and Miller said to use Soft Scrub Gel cleaner with bleach. The company’s nonabrasive cleaner is called Soft Scrub with Bleach Cleaner Gel ($2.89 for a 28.6-ounce bottle at Target) and comes in a green bottle, not white.