Your question includes two characters:
Clarity is measured visually and according to standards. You can review the guidelines, below.
If by 'you' you mean 'U', and you're query is about clarity and not colour, it is possible that 'U' indicates unenhanced. Unenhanced diamonds are more valuable than enhanced diamonds.
Not all diamonds are clear. Take your diamond to a jewelery store or a gemologist and ask for an evaluation of your diamonds. The lack of clarity can affect its value.
The initial J refers to colour, not clarity. On the scale of colourless diamonds, J fits into the range of slightly yellow.
Diamonds are graded in four ways: usually called the 4 Cs: color, carat weight, cut and clarity.The most important aspects are: color and clarity:Clarity ranges runs from Flawless and Internally Flawless, and includes VVS (very, very slight imprefections) to I which means that the diamonds is included with visible spots or cuts -- whatevers, that change how it appears. Included diamonds are the least expensive diamonds sold as jewelery.Color begins at D and runs through Z. D means very white, F means very good, G-H means good color, and I- Z indicates that there is more yellow visible to the naked eye the further down the alphabet the grade is applied. Some cheaper jewelry made by the millions uses clarity I and less white diamonds because they cost less as raw materials.Carat weight speaks for itself: it's the weight of the stone.Cut can be princess, round, trillion, and so forth.So, for example, if a diamond is clarity VVS, color: D, it is an excellent, probably a more expensive diamond. A good range is E-H, clarity: VVS - SI.The more flawed a stone, the less expensive it will beThe closer the letters get to I and further down the alphabet indicate that the diamond is a lot less desirable, and probably should be a lot cheaper.Your jeweler can tell you more, and you can look up all the information you need to learn about diamonds. Research before you buy, because not every jeweler is honest, although a good jeweler should be.You can ask for a certified gemological certificate for the stone you are buying, so that you know the unique physical properties of your investment. This is different from a jeweler's appraisal.
Clarity H-I sounds more like the colour grade. Clarity I2-i3 means that there are two or three visible inclusions in the diamond. This is the lowest clarity grade for gem-stone quality diamonds.
The clarity of the response required no further inquiry. Diamonds and wine are judged by their clarity.
Clarity is relative, some diamonds are hardly clear at all.
Cut diamonds are valued by their cut, clarity, carat weight and colour.
Diamonds are rated according to the colour, clarity, carat weight and cut.
Clarity is measured visually and according to standards. You can review the guidelines, below.
If by 'you' you mean 'U', and you're query is about clarity and not colour, it is possible that 'U' indicates unenhanced. Unenhanced diamonds are more valuable than enhanced diamonds.
IMP1 is not an acronym commonly association with diamonds.
Clarity enhanced diamonds are real, mined diamonds that have had their clarity/quality improved by cleaning and cloaking any visible imperfections in the diamond. Clarity enhanced diamonds are lower in price than 100% natural diamonds and therefore for every given carat weight and quality, the price will be lower. Clarity enhanced diamonds are graded after the enhancement and therefore if the diamond was originally F/SI1 and is now F/VS2, it will be priced lower as if it were still F/SI1, however will look like F/VS2. (see related link)
Diamonds are valued by cut, colour, clarity and colour. Without those details, pricing 19 diamonds is not possible.
Diamonds are graded according to clarity, colour, cut and carat weight, basically in that order of priority.
Althoguh clarity or color enhanced diamonds are "safe" to buy, they should be dramatically discounted from the price of natural diamonds.