You might have either etched the glossy glazed ceramic tile or abraded it with the brush. Some high gloss tiles contain a glaze that is simple to scratch and acid-sensitive. Diluted phosphoric acid is typically harmless if diluted appropriately. If the acid is overly corrosive then it will likely to give it a dull grainy look. If it is scraped with a brush it might dull it and give it a scratched appearance. Depending on the kind of tile body and the state of the glaze you may be able to highlight it with a sealer or something, but all you can do is carefully try. Find a replacement tile that matches. 
Flooring contractors sometimes store additional tiles in the garage or storage area for when the homeowner may need to fix tile disasters. Choose a matching grout. Borrow colored grout samples from a well-stocked flooring supply shop and bring it home to locate the closest match. Remove the old tile entirely. Be cautious not to harm any of the neighboring tiles. Use an electric drill with a masonry bit to drill a diagonal sequence of tiny holes into the cracked tile, maintaining drilled holes less than 1 inch 2.54 cm apart. Split the tile through the horizontal hole-line by using a ball-peen hammer to pound a cold chisel into the tile. Tap extremely softly so as not to damage adjoining grout joints. Remove the loosened parts. Use a flat bar to pry up any shards that you cannot pull up by hand. Scrape the remaining old mortar from the subfloor using a stiff-bladed scraper. It is not vital that you get every last piece up. Just make sure the region is pretty clear of mortar. Vacuum up any loose dirt or debris.
Tile repair kit
All the cracked floor and dented bathroom wall of your household there's not a single definition that will justify your home's appearance once the guests start to get. Favorited revolutionary tub and stone repair kit makes expert repairs on tile, stone, marble, and concrete a reality Without burning a hole through your pocket, of course. The porcelain repair kit contains an include agent that can be mixed to achieve the certain color and consistency, depending on the material you need to restore. 
The market is flooded with plenty of repair kits for different surfaces and fixtures in your household. Why spend on all of them if you can use a single tile and store repair agent for all your home repair emergencies. Fix a floor, rehabilitate tile paint, and unravel your bathroom and kitchen fixture's beauty. Homeowners trust granite filler repair kit because of its unparalleled color-matching compatibility. Our unique formula is well-suited for the usual shades. The stone repair kit also contain subtle tones and grain-matching and formula guide. You can set a firm date on your wall and floor repair without needing anyone's help. Our tile gap filler and repair for tile paint includes putty, color tints, lacquer, graining cotton swab, brush, mixing spatula, bowl, and mixing board. The formula guide will come in handy in creating complex shades. What makes our tile and stone repair kit a standout?—pure convenience. Everything you’ll need is inside the kit. Once you receive the tile crack repair kit, you’re only a few steps closer towards dent and scratch-free floors, walls, and ceramic fixtures. Simply add the putty on the bowl and stir. Afterward, squeeze the tint compound onto the mixture. After mixing, use the stick and apply to the damaged area.
How to fix a chipped tile without replacing it
When it comes to why tiles crack and need to be fixed, is put under too much stress that results in the material giving way and fracturing. With specific technique it's possible fix crack without replacing. 
These can be hairline cracks or more severe shattering, depending on the amount of strain the tile is put under. Made from hard ceramic or porcelain that undergoes high heat and pressure during manufacturing, tiles are well-equipped to withstand heavy bearing loads, footfall, extreme temperature fluctuations, exposure to moisture, and not to mention their fair share of impacts. The problem often comes when external factors undermine their individual strength and durability. Even if you don’t have a vast understanding of the science involved in tile production and installation, it doesn’t take a physics degree to know that any material will eventually break when put under pressure. This is exactly what happens with tiles. Due to their rigid format, there’s little to no give in tiles once they’re in situ, meaning they rely on their surrounding environment to support them and ensure they remain in place and intact. For instance, in the situation where the surface tiles are laid on is unstable or cracked, the tiles will be pulled in two different directions that puts stress on them in opposing areas. The result is a visible split in the tile surface. Similarly, if they’re undergoing strain due to heavy loads and aren’t the right tile for this application, it’s only a matter of time before the tile begins to buckle under the pressure of excessive weight. It also doesn’t take a genius to work out that if you drop a heavy item from height, like a casserole pot or heavy-based saucepan, this will apply pressure and stress in a concentrated area of the tile.
Fix chipped tile with nail polish
Fixing chipped tiles with nail polish is an easy method to use while fixing a broken or chipped tile is by applying nail polish over it. Do you have in tile in a kitchen, bathroom or other part of your home that is chipped? 
Even a little chip can really make the whole design look old, cheap, ruined and essentially destroyed! It is also not super easy or practical to replace a tile in any part of your house by this sort of mishap! Well, you can fix the look in seconds with this trick and it is really smart and a really good trick to save the look and save loads of money and headache! Simply grab a nail polish in as close to this color as possible and then paint over the chip and it will easily be camouflage in the tile. It make take a few coats! You can even fill in the hole with caulk, smooth it out and then paint as well if your chip is bad enough to make a noticeable pock mark. Also nail polish is a great way to ensure that the broken tile doesn’t break any further and color matches the tile. Nail polish will stay for a long time and wouldn’t come off that easily. You can use a mixture of various polishes to get the required color. Once you have the color you like, apply the color on the cracks with the nail polish brush. You can even create textures of the tile with the help of nail polish, a luxury you don’t get while using paints. Make sure to let it dry for a significant amount of time.
Porcelain tile chip repair
replacing the chipped tile. Sometimes you have to do that because the chip is so big that you may not have the skill set to repair it using the second method I’ll describe. 
If you decide to remove a ceramic floor tile, first make sure you have an exact match of the tile. I feel that builders and remodelers should always leave behind spare tile, in the boxes it came in. It should keep the tile and hand it off to future owners when they sell the home. saving the spare tile, it would be great if you had some of the original sanded grout. It’s harder to preserve sanded grout because the Portland cement in the product wants to harden as it’s exposed to humid air. To preserve it, you need to place it in a tightly sealed container and freeze it. The air inside most freezers is exceptionally dry. If you don’t have any spare grout, then you have to match it. If you don’t get a perfect match, the new grout line surrounding the replaced tile will look worse than the current chip! If you do decide to replace the tile, then you need to deep clean the tile and grout first and allow the grout to dry so you can see its true color. add just enough epoxy so it flows and is the same level as the surrounding glazed finish. This area of the tile often has a slightly rounded profile, and you don’t want the epoxy to run down onto the grout. Add the epoxy in at least two applications and build up layers over a period of 30 minutes. Epoxy placed and the chip is filled to the right height and profile, you paint the epoxy with a matching paint
How to fix chipped tile edges
Any ceramic tile can chip, but some tiles are more chip resistant than others. Normally the way we can tell if the edge of a tile was chipped prior to installation is by seeing if there is grout in the chipped edges. 
If the chip is right at the edge of the tile then it would normally be filled with grout if the chip was pre-existing. If there is no grout in the chipped spot, then it likely chipped after the tile was installed and grouted. If you have any left over tile, I would look at it to determine if its edges are chipped the same way they are on the installed tile. If the extra tile is chipped, then it was probably delivered that way. Perhaps it chipped during transportation? If so, there should be chip pieces in the box. The tile should not be supplied with chips. That is considered a defect. If the tiles were chipped prior to installation, then they should have never been installed. The tile installer should have noticed and not used those tiles. If the tiles were chipped after they were installed that would be surprising because tiles should not be that sensitive. Normally it requires a substantial impact for tiles to chip. It is possible that the ceramic tile is poor quality and has a propensity of chip, but not likely. There are epoxy paints or colorants where you can paint chipped spots so they are not as noticeable, but that is about all you can do to repair it short of replacement.
Tile crack repair epoxy
Epoxy is, essentially, a hardening mixture that you can use to "glue" together with the 2 pieces of your cracked tile. While there are 1-part epoxy kits, the 2-part variety is higher quality and will hold your cracked tile together for longer. 
Pour a little rubbing alcohol onto 1 or 2 sheets of paper towel. Wipe the damp paper towel over the surface of the cracked tile until it’s clean. Cleaning the cracked tile will remove any dust and grime and ensure that the epoxy sticks to the surface of the tile itself. Take your Popsicle stick and scoop up about half of the mixed epoxy. Transfer the epoxy to the tile and carefully spread a thin layer of epoxy along the entire length of the crack. The liquid will slowly seep down into the crack before it hardens. While the epoxy is drying, don’t touch it or set anything on top of it. Also, don't touch them and use the sharp edge of a blade to scrape away any stray epoxy that got onto the tile. To clean off the epoxy, hold the blade at a 45-degree angle against the surface of the tile. Slide under excess epoxy to remove it. Ideally, you’ll have a spare tile or 2 left over from when the tile floor or counter was installed. Put on a pair of latex gloves before you start working with mortar. Hold the tile so that it’s centered over the hole that you removed the original tile from. Set the tile and press down lightly. Before the grout dries, dampen a rag or old washcloth and use it to rub the new tile clean.