Crude but works.
Public Function AcadToRGB&(ByVal Col&)
Dim r&, g&, b&
Select Case Col
Case 1: AcadToRGB = 255: Exit Function
Case 2: AcadToRGB = 65535: Exit Function
Case 3: AcadToRGB = 65280: Exit Function
Case 4: AcadToRGB = 16776960: Exit Function
Case 5: AcadToRGB = 16711680: Exit Function
Case 6: AcadToRGB = 16711935: Exit Function
Case 7: AcadToRGB = 16777215: Exit Function
Case 8: AcadToRGB = 8355711: Exit Function
Case 9: AcadToRGB = 12566463: Exit Function
Case 10: AcadToRGB = 255: Exit Function
Case 11: AcadToRGB = 8355839: Exit Function
Case 12: AcadToRGB = 207: Exit Function
Case 13: AcadToRGB = 6316239: Exit Function
Case 14: AcadToRGB = 144: Exit Function
Case 15: AcadToRGB = 5197712: Exit Function
Case 16: AcadToRGB = 127: Exit Function
Case 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 110, 112, 114, 116, 118,
120, 122, 124, 126, 128, 130, 132, 134, 136, 138, 140, 142, 144, 146, 148,
150, 152, 154, 156, 158, 160, 162, 164, 166, 168, 170, 172, 174, 176, 178: r
= 0
Case 88, 188: r = 15
Case 86, 186: r = 31
Case 78, 84, 99, 109, 119, 129, 139, 149, 159, 169, 179, 184, 198: r = 32
Case 82, 89, 182, 189, 250: r = 47
Case 68, 79, 199, 208: r = 48
Case 69, 76, 80, 97, 107, 117, 127, 137, 147, 157, 167, 177, 180, 196, 209:
r = 63
Case 18, 19, 28, 29, 38, 39, 48, 49, 58, 59, 74, 87, 95, 105, 115, 125, 135,
145, 155, 165, 175, 187, 194, 218, 219, 228, 229, 238, 239, 248, 249: r = 79
Case 66, 77, 185, 197, 206: r = 95
Case 72, 85, 93, 103, 113, 123, 133, 143, 153, 163, 173, 192: r = 96
Case 64, 67, 75, 195, 204, 207: r = 111
Case 17, 26, 27, 36, 37, 46, 47, 56, 57, 70, 83, 91, 101, 111, 121, 131,
141, 151, 161, 171, 183, 190, 216, 217, 226, 227, 236, 237, 246, 247: r =
127
Case 65, 205, 252: r = 128
Case 24, 25, 34, 35, 44, 45, 54, 55, 62, 73, 193, 202, 214, 215, 224, 225,
234, 235, 244, 245: r = 144
Case 81, 181: r = 159
Case 63, 203, 253: r = 175
Case 60, 71, 191, 200: r = 191
Case 22, 23, 32, 33, 42, 43, 52, 53, 212, 213, 222, 223, 232, 233, 242, 243:
r = 207
Case 61, 201: r = 223
Case 20, 21, 30, 31, 40, 41, 50, 51, 210, 211, 220, 221, 230, 231, 240, 241,
255: r = 255
Case 251: r = 80: g = 80: b = 80
Case 254: r = 208: g = 208: b = 208
End Select
Select Case Col
Case 18, 170, 172, 174, 176, 178, 180, 182, 184, 186, 188, 190, 192, 194,
196, 198, 200, 202, 204, 206, 208, 210, 212, 214, 216, 218, 220, 222, 224,
226, 228, 230, 232, 234, 236, 238, 240, 242, 244, 246, 248: g = 0
Case 28, 168: g = 15
Case 26, 166: g = 31
Case 19, 24, 38, 158, 164, 179, 189, 199, 209, 219, 229, 239, 249: g = 32
Case 22, 29, 162, 169, 250: g = 47
Case 39, 48, 148, 159: g = 48
Case 17, 20, 36, 49, 149, 156, 160, 177, 187, 197, 207, 217, 227, 237, 247:
g = 63
Case 18, 27, 34, 58, 59, 68, 69, 78, 79, 88, 89, 98, 99, 108, 109, 118, 119,
128, 129, 138, 139, 154, 167, 175, 185, 195, 205, 215, 225, 235, 245: g = 79
Case 152: g = 86
Case 25, 37, 46, 146, 157, 165: g = 95
Case 32, 173, 183, 193, 203, 213, 223, 233, 243: g = 96
Case 35, 44, 47, 144, 147, 155: g = 111
Case 23, 30, 56, 57, 66, 67, 76, 77, 86, 87, 96, 97, 106, 107, 116, 117,
126, 127, 136, 137, 150, 163, 171, 181, 191, 201, 211, 221, 231, 241: g =
127
Case 45, 145, 252: g = 128
Case 33, 42, 54, 55, 64, 65, 74, 75, 84, 85, 94, 95, 104, 105, 114, 115,
124, 125, 134, 135, 142, 153: g = 144
Case 21, 161: g = 159
Case 43, 143, 253: g = 175
Case 31, 40, 140, 151: g = 191
Case 52, 53, 62, 63, 72, 73, 82, 83, 92, 93, 102, 103, 112, 113, 122, 123,
132, 133: g = 207
Case 41, 141: g = 223
Case 50, 51, 60, 61, 70, 71, 80, 81, 90, 91, 100, 101, 110, 111, 120, 121,
130, 131, 255: g = 255
End Select
Select Case Col
Case 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52,
54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90,
92, 94, 96, 98: b = 0
Case 108, 248: b = 15
Case 106, 246: b = 31
Case 19, 29, 39, 49, 59, 69, 79, 89, 99, 104, 118, 238, 244: b = 32
Case 102, 109, 242, 249, 250: b = 47
Case 119, 128, 228, 239: b = 48
Case 17, 27, 37, 47, 57, 67, 77, 87, 97, 100, 116, 129, 229, 236, 240: b =
63
Case 25, 35, 45, 55, 65, 75, 85, 95, 107, 114, 138, 139, 148, 149, 158, 159,
168, 169, 178, 179, 188, 189, 198, 199, 208, 209, 218, 219, 234, 247: b = 79
Case 105, 117, 126, 226, 237, 245: b = 95
Case 23, 33, 43, 53, 63, 73, 83, 93, 112, 232: b = 96
Case 115, 124, 127, 224, 227, 235: b = 111
Case 21, 31, 41, 51, 61, 71, 81, 91, 103, 110, 136, 137, 146, 147, 156, 157,
166, 167, 176, 177, 186, 187, 196, 197, 206, 207, 216, 217, 230, 243: b =
127
Case 125, 225, 252: b = 128
Case 113, 122, 134, 135, 144, 145, 154, 155, 164, 165, 174, 175, 184, 185,
194, 195, 204, 205, 214, 215, 222, 233: b = 144
Case 101, 241: b = 159
Case 123, 223, 253: g = 175
Case 111, 120, 220, 231: b = 191
Case 132, 133, 142, 143, 152, 153, 162, 163, 172, 173, 182, 183, 192, 193,
202, 203, 212, 213: b = 207
Case 121: b = 223
Case 130, 131, 140, 141, 150, 151, 160, 161, 170, 171, 180, 181, 190, 191,
200, 201, 210, 211, 221, 255: b = 255
End Select
AcadToRGB = RGB(r, g, b)
End Function