OK you've successfully goaded me into providing an example.  Here 'tis.  Colors were set up manually; you could probably program this easily.

// Create a conditional formatting rule that uses rainbow colors for 0-100
preferences(
      Conditional Formatting Rules(
            RuleSet(
                  RuleName( "Gradient 0-100" ),
                  Range( MinValue( 0 ), MaxValue( 10 ), InclusiveStart( 0 ), InclusiveEnd( 1 ),
                        EndBackColor( {240, 78, 0} ), Format( Back Color( {255, 0, 0} ) )
                  ),
                  Range( MinValue( 10 ), MaxValue( 20 ), InclusiveStart( 0 ), InclusiveEnd( 1 ),
                        EndBackColor( {208, 254, 24} ), Format( Back Color( {243, 147, 1} ) )
                  ),
                  Range( MinValue( 30 ), MaxValue( 40 ), InclusiveStart( 0 ), InclusiveEnd( 1 ),
                        EndBackColor( {29, 254, 34} ), Format( Back Color( {242, 254, 10} ) )
                  ),
                  Range( MinValue( 40 ), MaxValue( 50 ), InclusiveStart( 0 ), InclusiveEnd( 1 ),
                        EndBackColor( {35, 254, 210} ), Format( Back Color( {51, 254, 22} ) )
                  ),
                  Range( MinValue( 50 ), MaxValue( 60 ), InclusiveStart( 0 ), InclusiveEnd( 1 ),
                        EndBackColor( {4, 11, 255} ), Format( Back Color( {44, 233, 254} ) )
                  ),
                  Range( MinValue( 60 ), MaxValue( 70 ), InclusiveStart( 0 ), InclusiveEnd( 1 ),
                        EndBackColor( {122, 14, 254} ), Format( Back Color( {16, 34, 254} ) )
                  ),
                  Range( MinValue( 70 ), MaxValue( 80 ), InclusiveStart( 0 ), InclusiveEnd( 1 ),
                        EndBackColor( {254, 18, 236} ), Format( Back Color( {114, 10, 254} ) )
                  ),
                  Range( MinValue( 80 ), MaxValue( 90 ), InclusiveStart( 0 ), InclusiveEnd( 1 ),
                        EndBackColor( {254, 14, 152} ), Format( Back Color( {237, 9, 255} ) )
                  ),
                  Range( MinValue( 90 ), MaxValue( 100 ), InclusiveStart( 0 ), InclusiveEnd( 1 ),
                        EndBackColor( {244, 0, 18} ), Format( Back Color( {255, 21, 145} ) )
                  )
            )
      ),
);
// Create a table to test things out with
dt = New Table( "test gradient", Add Rows( 10 ),
      New Column( "Factor1", Numeric, Continuous, Format( "Best", 12 ),
            Set Values(
                  [13.6854337062687, 17.3569041769952, 17.9111931007355, 49.1005608113483,
                  57.4445765465498, 57.5570550980046, 61.441846890375, 70.2064076205715,
                  77.4806626606733, 94.3617827259004] ) ),
      New Column( "Factor2", Numeric, Continuous, Format( "Best", 12 ),
            Set Values(
                  [23.8564028637484, 82.8440769342706, 6.53149569407105, 65.9139207797125,
                  24.9276944668964, 29.2392280884087, 7.34108469914645, 65.837666625157,
                  87.6187813701108, 64.2478915164247] ) ) 
);
// Create a window using all of this
f1_list = dt:factor1 << get values;
f2_list = dt:factor2 << get values;
new window("Big Class Gradient",
      tablebox(
            ncb1 = numbercolbox("Factor 1", f1_list),
            ncb2 = numbercolbox("Factor 2", f2_list),
      ),
);
ncb1 << set conditional format("Gradient 0-100");
ncb2 << set conditional format("Gradient 0-100");