according to a first aspect of the present invention , a system has been developed whereby the various cuts of a diamond are defined in terms of individual user preferences . that is , the various cuts of a diamond are assessed according to factors that characterize the beauty and desirability of the diamond . in this regard , three factors are commonly used to assess the beauty of a diamond being brilliance , fire or dispersion and scintillation . brilliance is generally considered to be the most important feature when considering diamond beauty . if brilliance is compromised then the effectiveness of a diamond &# 39 ; s fire and scintillation is also reduced . brilliance is often related to proportions that reduce light loss from the pavilion of a diamond . the understanding of brilliance must include the directions in which light travels to an observer and the source and type of light used in any analysis . fire is the term used to describe the spectral separation or dispersion of white light into rainbow flashes . fire is generally considered to be enhanced with steeper crown angles and smaller tables . scintillation is perhaps the least clearly defined visual feature in diamond appearance . one definition is “ a pleasing visual balance in the spread of clearly defined and well spread dark and light areas that flash on and off as a light source , the stone or the observer &# 39 ; s position change ”. the dark areas should be a small component of the overall stone &# 39 ; s face up appearance with a head shadow of 21 degrees . scintillation is dependent on the type of lighting , the observer &# 39 ; s physical presence and the diamond itself . it is more personal than brilliance and fire , because the more of these two features the better , whereas the ideal amount of blackness and contrast is in the eye of the beholder . a further desirability factor that may be considered in the system according to the present invention is “ diameter spread ”. that diamonds of the same weight but different proportions can appear bigger or smaller is often referred to as “ spread ”. this factor , however , is an economic or desirability factor rather than a beauty factor . according to a first embodiment of the invention , the system is fed various cut features of a diamond , such as crown and pavilion angles and table percentage . based upon the actual values , input , the system produces a simple description of the visual appearance of the diamond in terms of the beauty factors of the diamond . therefore , in this way , rather than just providing a numeric grade , the customer is provided with a definition from which the individual is able to form their own opinion , based upon personal or regional taste . in this regard , the present invention uses a look - up table or the like which matches diamonds having particular cut features with appropriate beauty factors . in this regard , according to the first embodiment of the invention , weightings are given to all of the factors being considered , such as : from these weightings it is apparent that the system is based upon holistic information , rather than unrelated individual features , and that the feature considered most important in assessing diamond beauty is brilliance . in order to apply the holistic information to particular diamond cuts , a cross correlation between the various cuts and the holistic information needs to be established . this may be achieved in various ways , such as by studying actual diamonds in order to calculate penalty values . however , it is more efficiently performed using virtual diamond analysis , as this eliminates problems with variation in color , clarity and the minor facet groups . examples of software programs that may be utilised include diamcalc ™, firescope ™ and gilbertson - scope . these software packages are available from octonus software limited , a company founded by moscow state university , russia . such software programs may be used to develop charts of diamond images of the most commonly encountered diamond proportions . for the present example , the range chosen was for table sizes between 54 % and 65 % on a grid of the pavilion angles between 39 . 5 ° and 43 ° in 0 . 5 ° graduations and steps of one degree for crown angles between 28 ° and 40 °. the firescope ™ instrument , as distinct from the firescope ™ software , enables the light return of real diamonds to be studied and appropriate weightings given in regard to brilliance . in this regard , using the virtual firescope software , it has been found that consumers show a preference for diamonds with a strong red light return and a black eight star pattern . therefore , using the firescope ™ software , diamonds displaying this feature were given a good brilliance rating . from this analysis it became apparent that as table size increases , the black stars in the stones identified as falling within the recommended areas are seen to become thinner and less well defined . also , it became apparent that variations in pavilion angles could be compensated for by a larger opposing variation in crown angles . this resulted in a broader range of proportions than the tolkowsky proportions that yielded beautiful diamonds . therefore , such subjective analysis was applied to all the virtual diamonds in the grid patterns using the diamcalc software tools , predominantly from a “ face up ” position , and each given an appropriate brilliance score of zero to four , whereby the lower the score , the better the brilliance . in order to verify the results , cross correlation was performed by comparing diamonds with the same score from different areas on each grid , and those from other table size grids . finally results were confirmed by showing actual diamonds with known proportions to numerous observers in various lighting environments . fig2 illustrates graphically the comparative brilliance scores from one of the several charts devised for diamonds with varying crown and pavilion angles , and with a table size of 56 %. these results are based upon extensive research into consumer preferences and desired characteristics . it is therefore to be appreciated that these results are subjective and may be altered in order to cater for user preferences in particular brilliance characteristics . fig3 similarly illustrates graphically the comparative fire scores devised for diamonds with varying crown and pavilion angles , and with a table size of 56 %. these results were also based upon extensive research of consumer preferences and desired characteristics , and also aided by the use of software , such as diamcalc , that enables ray path analysis to be performed . further , fig4 illustrates graphically the comparative scintillation scores devised for diamonds with varying crown and pavilion angles , and with a table size of 56 %. scintillation is dependent on the type of lighting the observer &# 39 ; s physical presence and the diamond itself . the scores devised in fig4 were based upon charts that used a relative head size of 150 mm ( 6 inches ) from a distance of 407 mm ( 16 . 3 inches ) which is blocking 21 degrees of the 180 degrees of available light source above the plane of the girdle . fig5 illustrates comparative spread scores for diamonds with a 56 % table . the spread scores were devised by taking into account diamond weight , depth percentage as well as actual subjective beauty . it is to be appreciated that the results of fig2 , 3 and 4 and 5 were produced essentially by considering the face up viewing position of the diamond because of the economic importance of this position . this is because most diamond sales are made by observing diamonds from a face up view . nevertheless , this is not an essential component of the invention , and the model used in developing weightings could equally be based upon other viewing positions , such as oblique positions . although the aesthetic penalties in relation to brilliance , fire , scintillation and diameter spread are the most preferred qualities to account for , penalties or adjustments in relation to other aesthetic qualities may also be taken into account in the overall model . for example , in another embodiment of the invention , a further aesthetic feature of diamonds that may be taken into consideration in calculating a penalty weighting is vertical spread . vertical spread is different to diameter spread . it is an issue that consumers raise from time to time and is the amount of diamond that can be seen projecting above a setting . generally vertical spread comes at the cost of reducing “ diameter spread ”. for example , a somewhat subjective allowance for this factor could be a 20 % weighing in the spread factor for stones with steep crowns and small tables . generally , the best looking diamonds have table sizes of 53 % to 60 % ( measured as a percentage of the diameter of the diamond ). diamonds with table sizes that are too large or too small have some impact on diamond beauty . hence , it is preferable for a penalty factor for such table sizes to be applied to each of the beauty factors as follows : the arrows indicate that penalties continue below 50 % and above 65 % table sizes . hence , a diamond with a table size of 62 . 5 % has scores of brilliance of 0 . 5 , fire 0 . 643 and scintillation 0 . 643 giving a total penalty of 1 . 786 . this means it is possible for a diamond with this size table to score an excellent grade . in a still further embodiment of the invention , a further aesthetic feature that may be taken into consideration in calculating penalty weightings is an adjustment for the girdle thickness . ray path analysis shows that polished girdles refract some light back above the girdle in the same way as other facets . however , for this to occur , it would require a diamond to be set with an exposed girdle . nevertheless , on balance , thick girdles result in less light return and can look like inclusions , especially if bruted rather than faceted . thick , very thick and extremely thick girdles weigh much more but are one of the most effective ways to maintain yield without sacrificing beauty . diamonds with extremely thin and very thin girdles are given a penalty because of the undesirable risk of damage . it should be noted that the spread factor provides an additional penalty for a diamond with an overly thick girdle . with these considerations in mind , the following penalty deduction for overly thin and overly thick girdles : hence in the girdle range between 4 % and 10 %, the penalty is between zero to one on a continuum , and the continuum extends further for excessively large girdles . according to a further embodiment of the invention , an adjustment may be made for fish - eyes . a fish - eye appears as a circular inclusion and is a reflection of the girdle on the opposite side . fish eyes are most apparent if the pavilion is shallow and the table is large or a combination of the two . fish eyes can be seen in diamonds with a 41 ° pavilion and 72 . 2 % table and at 390 pavilion and 58 . 4 % table and any proportions in between , with no tilt . also , as the table gets 1 % bigger , a 1 % larger fish - eye is apparent . nevertheless , a near fish - eye may be considered desirable because the stone will have an excellent spread . in relation to the weightings given to diamonds evaluated using the present invention , a score of 1 is added for 0 % on a sliding scale where 5 % is given 0 . 2 . as fish - eyes are generally an undesirable trait , an automated comment in relation to the fish - eye should be generated for appropriate stones . for example : a small amount of tilt will show a fisheye under the the percentages in this table refer to the abc page - thiesen diamond grading scheme , although any suitable grading system may be utilised . a large culet on a diamond allows a small amount of light loss , but more importantly mars the appearance . in this regard , a culet often appears as a black inclusion . in order to account for this problem , if a culet size is smaller than 1 %, no penalty is added . however , for culet sizes above 1 %, a penalty is added on a sliding scale , with a 5 % culet size adding a penalty of 0 . 8 . with all required weightings and adjustments determined , these calculations may then be utilised in a user - friendly system for evaluating a diamond . in this regard , the system would operate by requiring a user to directly input the cut parameters of a diamond of interest , or via an interface with a proportion measuring device or other proportion data processing means . based upon the input parameters , the system will then match these parameters with the relevant tables of brilliance , fire , scintillation and spread ratings and other applicable adjustments in order to obtain an appropriate weighting for each factor , as well as a total score . an overall comment may also be provided . for example , for a diamond having a table of 56 %, a pavilion angle of 42 °, a crown angle of 31 °, a girdle of 2 % and a culet of 0 %, the diamond will obtain a weighting of 1 . 0 for brilliance , 1 . 0 for fire , 1 . 0 for scintillation and about 0 . 46 for spread . this diamond will therefore have an overall penalty of 3 . 46 . it is to be appreciated that the worst looking diamond would be rated as ten or more . a score of zero would be extremely uncommon , and in fact most popular tolkowsky proportioned diamonds would score around one . it is hence apparent that this penalty is based upon aesthetic principles and is therefore likely to have more meaning to a lay person . in addition to the numeric aesthetic penalty rating , it is possible to provide the user with a descriptive assessment of the diamond based upon the diamond cut parameters and / or the penalty weightings given for the aesthetic parameters of brilliance , fire , scintillation and spread . therefore , in simple words the system can describe how each diamond will most likely look to a buyer in a jewelry store lighting environment for each of the above parameters . for example , it is possible for the advisory system to recognise three distinct types of diamond with optimum beauty , being tolkowsky &# 39 ; s ideal cut ( tic ), brilliant ideal cuts ( bic ) and fiery ideal cuts ( fic ). brilliant ideal cuts return the most light and tend to have the largest spread for the same weight . fiery ideal cuts have more fire or spectral colour and appear to have more facets and scintillation . an fic is a cut with a steep crown angle in order to increase fire or dispersion , while having a slight reduction in pavilion angle to maintain optimum dispersion . a bic on the other hand is one with a shallower crown angle and slightly deeper pavilion in order to optimize brilliance . the tic range combines a balance of fire and brilliance . bic diamonds tend to weigh less and fic diamonds weigh more for the same diameter spread . therefore , when one of these stones is recognised , the system can include a statement in the assessment , such as : in this regard , bic , tic and fic characteristics are only given for diamonds in the excellent range ( ie less than 2 ) and with the following crown angles : the system can also provide an assessment based upon each feature being assessed . for example : 0 this diamond has ideal brilliance 1 this diamond has very good brilliance 2 this diamond has good brilliance 3 this diamond has fair brilliance 4 this diamond has poor brilliance 0 it has a very good “ spread ” or large diameter for its weight 1 it has a reasonable diameter or “ spread ” for its weight 2 it is deeply cut and has a poor “ spread ” or diameter for its weight 0 and the polish is excellent 0 . 5 and the polish is good 1 and the polish is poor 0 with a medium girdle ( very good ) 0 . 5 with a very thin girdle ( can chip ) 0 . 5 with a thicker than ideal girdle , so it weights about x % more than if it had a thinner girdle 0 . 5 this diamond has an extremely thin girdle that is prone to chipping , but the spread is bigger than you would expect 1 this diamond will lose some brilliance through its extremely thick girdle , it weighs about xx % more than it should the present invention therefore provides a system able to furnish a description of the visual appearance of diamonds in simple terms , even though the variables and issues involved are enormously complex . that is , the present invention is able to turn the numerical cut grades into a benefit based rating that defines the cut of a diamond in ways that individual preferences can be identified and satisfied . in particular the system aids both novice consumers and experienced buyers in selecting unseen diamonds , as if each diamond were lined up side by side . in fact , in a further embodiment of the invention , where the present advisory system is provided over the internet , a database could be formed by having a number of traders upload proportions of their diamonds that are for sale . the proportions would preferably be determined using proportion measuring devices , such as those manufactured by sarin technologies and ogi corporation . for example , sarin technologies market a desk - top measurement device that takes a series of 64 pictures of a rotating diamond and measure all its angles and proportions digitally . potential customers could then obtain reports using the advisory system in relation to these diamonds , based upon the proportion information , and also view virtual models of the diamonds , created from the proportion information by using virtual modeling tools , like diamcalc . in a further embodiment of the invention , proportion measuring devices are used to model every facet of a diamond making it then possible to account for symmetry and other faceting variations and defects , which are then able to be included in the advisory system . this would then enable a virtual image to be generated . alternatively , the image displayed to the user may be a digital photograph of the appropriate diamond . therefore , in addition to the user being given an aesthetic grading and appropriate comment on the diamond , an equivalent image of the diamond may be displayed before the user together with details relating to the relevant trader , such as a hot - link to the trader &# 39 ; s site . the present invention may also be advantageously used in overcoming the problems in existing grading systems , which include inadequate cuts within the “ top grades ” and exclude other diamonds with favourable combinations of rejected proportions . thus current systems unfortunately leads cutters to cut for grades and attract healthy margins , as compared to cutting for beauty . that is , diamond cutters will generally cut a diamond within the recognised tolerances of an “ ideal cut ” which weighs the most , but which typically is dull and drab , as they make more money by cutting deeper , heavier diamonds , that leave a little more weight on the crown and pavilion , even though in actuality , these are not the more beautiful diamonds . the present invention , however , may be used to redress this problem , in that the cut advisory system may be programmed into rough diamond analysis instruments . this will provide cutters with greater guidance as to the most appropriate dimensions to cut rough diamonds in order to maximise the yield of a rough diamond and to also produce a diamond of an acceptable grade . variations and additions are possible within the general inventive concept as will be apparent to those skilled in the art .