How to modify appraiser data?

DiamCalc allows to examine or modify data of appraisers, i.e. to change criteria which are used for diamond grading

Before examining or especially editing appraiser data you need to study Appraise.txt file format thoroughly. The best is to keep a printed copy of that document with you while working with Appraise.txt file. To study the data shipped with DiamCalc see how DiamCalc grades diamonds.

Please keep in mind that an incorrect modification of configuration files may make appraising not work. Please make a backup copy of Appraise.txt file before changing it. Having it will help to restore a working configuration if something goes wrong. It is especially important if you made some modifications of this file before, so there is a risk that your previous work can be lost. Let us look at the following examples of modifying Appraise.txt file. Note that data of all grading systems is stored in a similar format, so that you can use any of examples as a guideline for similar change in any of the supported grading systems.

1. Setting a different discount for a cut quality (example: 12% discount for Good quality in HRD system instead of 10%)
2. Setting a numerical range for a gradation of parameter (example: setting a border value between "Very thin" and "Thin" girdles in AGA system to 1.1% of diameter instead of 1.0%)
3. Setting a range for a parameter in a quality group (example: defining a range of Good crown angle in GIA system as 33-35% of diameter instead of 32-36%)

1. Setting a different discount for a cut quality

Example: 12% discount for Good quality in HRD system instead of 10%

1. Open Appraise.txt file with a text editor of your choice (e.g. Notepad).
2. Find a section of the file where HRD data is listed. Browse the file for "[Appraiser]" lines. There are several such lines, each for a supported marking system. Find the one which is preceded by comment "; HRD" (";" denotes beginning of a comment). There is "Title: HRD" text somewhat below.
   Tip: use your text editor's search capabilities to find "[Appraiser]" lines.
3. There is a list of all quality groups at the beginning of HRD section. Look for a "[quality]" line, it is followed by several quality group names accompanied by discount values. There is a "Good 10" line which means that the Good diamonds are currently discounted by 10%. Change the value of "10" to "12" and save the file.
4. The next time DiamCalc is started, new discount value for Good diamonds in HRD system will be used.

2. Setting a numerical range for a gradation of parameter

Example: setting a border value between "Very thin" and "Thin" girdles in AGA system to 1.1% of diameter instead of 1.0%

1. Open Appraise.txt file with a text editor of your choice (e.g. Notepad).
2. Find a section of the file where AGA data is listed. Browse the file for "[Appraiser]" lines. There are several such lines, each for a supported marking system. Find the one which is preceded by comment "; AGA (GEMS & GEMOLOGY Fall 1998 p. 164)" (";" denotes beginning of a comment). There is "Title: AGA" text somewhat below.
   Tip: use your text editor's search capabilities to find " [Appraiser]" lines.
3. Find the "[other]" section (it begins with "[other]" line and ends with the next "[end]" line). Find a line that begins with "StringValue: GirdleHeight_GIA (%)". Grades of girdle height follow. After each one, there is a pair of values which means minimum and maximum values for this grade. For example, "Thin 1.0 1.5" means that Thin girdle is one with height between 1.0 and 1.5% of diameter. To modify a border value between Very thin and Thin girdles, change values for both gradations: substitute "Thin 1.0 1.5" by "Thin 1.1 1.5" and "Very thin" 0.4 1.0" by "Very thin" 0.4 1.1".
4. The next time DiamCalc is started, it will place a border between "Thin" and "Very thin" girdles in AGA system at 1.1% of diameter.

3. Setting a range for a parameter in a quality group

Example: defining a range of Good crown angle in GIA system as 33-35% of diameter instead of 32-36%.

1. Open Appraise.txt file with a text editor of your choice (e.g. Notepad).
2. Find a section of the file where GIA data is listed. Browse the file for "[Appraiser]" lines. There are several such lines, each for a supported marking system. Find the one which is preceded by comment "; GIA" (";" denotes beginning of a comment). There is "Title: GIA" text somewhat below. Tip: use your text editor's search capabilities to find "[Appraiser]" lines.
3. Scroll down the file to find a section of GIA data where parameters for Brilliant cut are stored. It begins with "[cut]" end ends with the next "[end]" line. Between those lines, there should be "Name: Brilliant" line and a line beginning with "Mass: 0.01 100000". It means that the section between "[cut]" and "[end]" line refers to diamonds of Brilliant cut with any mass (from 0.01 to 100000 carat).
   Note: if you would like to modify an appraiser which supports different cuts (e.g. AGA appraiser), there will be several "[cut]"..."[end]" sections, each one for a different cut or for different range mass. For example, there is a "[cut]"..."[end]" section in AGA data which is relevant to Pear cut only; it can be found by line "Name: Pear" between "[cut]" and "[end]" lines.
4. Find a line beginning with "Mass: 0.01 100000" in the section. After it, a block of data follows. To understand it, look at several lines just before "Mass...." line. "Quality: "E-VG" G F" means that there is data for three quality groups: Excellent/Very good, Good and Fair. After "Mass: 0.01 100000", the data for quality groups follows, one line for each group.
   We are going to modify Good crown angle data, so we select the second line for Good group (remember, their order was "E-VG G F", so G (Good) is the second one). The line begins with "32 36 42 44 Thin Thick ...". To understand the meaning of this, look at the line above that begins with "Parameters: UpAngle (°) DownHeight_GIA (%) GirdleHeight_mm (s)...". There are two values in the data line for each parameter, and the line can be read as follows: Good group has first parameter (UpAngle, i.e. crown angle) between 32 and 36 degrees, second parameter (DownHeight, i.e. pavilion height) between 42 and 44% of diameter, third parameter (GirdleHeight, i.e. girdle thickness) from Thin to Thick, etc. To complete what we were going to do, correct "32" by "33" and "36" by "35".
5. The next time DiamCalc is started, the Good group for Crown angle in GIA system will be defined as being from 33 to 35 degrees.