Nice implementation of the mixin which will generate child classes with colors. This file will create many count of color classes (.blue-grey, blue-grey-lighten-1, blue-grey-text-lighten )

pretty-colors.less

    // MIXIN
    .make-sub-colors(@colors, @prefix) {
        .sub-color(@index) when (@index =< length(@colors)) {
          @value: extract(@colors, @index);
          @item: ~".@{prefix}-@{index}";
          &@{item} {
            color: @value !important;
          }
          .sub-color(@index + 1);
        }
        .sub-color(1);
    }


    .materialize-red{
        background-color: #e51c23 !important;
        @lighten-colors: #ea454b, #ee6e73, #f3989b, #f8c1c3, #fdeaeb;
        @darken-colors: #d0181e, #b9151b, #a21318, #8b1014;
        .make-sub-colors(@lighten-colors, "lighten");
        .make-sub-colors(@darken-colors, "darken");
        &-text{
            color: #e51c23 !important;
            .make-sub-colors(@lighten-colors, "text-lighten");
            .make-sub-colors(@darken-colors, "text-darken");
        }
    }

    .red{
        background-color: #F44336 !important;
        @lighten-colors: #EF5350, #E57373, #EF9A9A, #FFCDD2, #FFEBEE;
        @darken-colors: #E53935, #D32F2F, #C62828, #B71C1C;
        @accent-colors: #FF8A80, #FF5252,#FF1744,#D50000;
        .make-sub-colors(@lighten-colors, "lighten");
        .make-sub-colors(@darken-colors, "darken");
        .make-sub-colors(@accent-colors, "accent");
        &-text{
            color: #F44336 !important;
            .make-sub-colors(@lighten-colors, "text-lighten");
            .make-sub-colors(@darken-colors, "text-darken");
            .make-sub-colors(@accent-colors, "text-accent");
        }
    }

    .pink{
        background-color: #e91e63 !important;
        @lighten-colors: #ec407a, #f06292, #f48fb1, #f8bbd0, #fce4ec;
        @darken-colors: #d81b60, #c2185b, #ad1457, #880e4f;
        @accent-colors: #ff80ab, #ff4081,#f50057,#c51162;
        .make-sub-colors(@lighten-colors, "lighten");
        .make-sub-colors(@darken-colors, "darken");
        .make-sub-colors(@accent-colors, "accent");
        &-text{
            color: #e91e63 !important;
            .make-sub-colors(@lighten-colors, "text-lighten");
            .make-sub-colors(@darken-colors, "text-darken");
            .make-sub-colors(@accent-colors, "text-accent");
        }
    }

    .purple{
        @default-color: #9c27b0;
        @lighten-colors: #ab47bc, #ba68c8, #ce93d8, #e1bee7, #f3e5f5;
        @darken-colors: #8e24aa, #7b1fa2, #6a1b9a, #4a148c;
        @accent-colors: #ea80fc, #e040fb,#d500f9,#aa00ff;
        background-color: @default-color !important;
        .make-sub-colors(@lighten-colors, "lighten");
        .make-sub-colors(@darken-colors, "darken");
        .make-sub-colors(@accent-colors, "accent");
        &-text{
            color: @default-color !important;
            .make-sub-colors(@lighten-colors, "text-lighten");
            .make-sub-colors(@darken-colors, "text-darken");
            .make-sub-colors(@accent-colors, "text-accent");
        }
    }

    .deep-purple{
        @default-color: #673ab7;
        @lighten-colors: #7e57c2, #9575cd, #b39ddb, #d1c4e9, #ede7f6;
        @darken-colors: #5e35b1, #512da8, #4527a0, #311b92;
        @accent-colors: #b388ff, #7c4dff,#651fff,#6200ea;
        background-color: @default-color !important;
        .make-sub-colors(@lighten-colors, "lighten");
        .make-sub-colors(@darken-colors, "darken");
        .make-sub-colors(@accent-colors, "accent");
        &-text{
            color: @default-color !important;
            .make-sub-colors(@lighten-colors, "text-lighten");
            .make-sub-colors(@darken-colors, "text-darken");
            .make-sub-colors(@accent-colors, "text-accent");
        }
    }

    .indigo{
        @default-color: #3f51b5;
        @lighten-colors: #5c6bc0, #7986cb, #9fa8da, #c5cae9, #e8eaf6;
        @darken-colors: #3949ab, #303f9f, #283593, #1a237e;
        @accent-colors: #8c9eff, #536dfe,#3d5afe,#304ffe;
        background-color: @default-color !important;
        .make-sub-colors(@lighten-colors, "lighten");
        .make-sub-colors(@darken-colors, "darken");
        .make-sub-colors(@accent-colors, "accent");
        &-text{
            color: @default-color !important;
            .make-sub-colors(@lighten-colors, "text-lighten");
            .make-sub-colors(@darken-colors, "text-darken");
            .make-sub-colors(@accent-colors, "text-accent");
        }
    }

    .blue{
        @default-color: #2196F3;
        @lighten-colors: #42A5F5, #64B5F6, #90CAF9, #BBDEFB, #E3F2FD;
        @darken-colors: #1E88E5, #1976D2, #1565C0, #0D47A1;
        @accent-colors: #82B1FF, #448AFF,#2979FF,#2962FF;
        background-color: @default-color !important;
        .make-sub-colors(@lighten-colors, "lighten");
        .make-sub-colors(@darken-colors, "darken");
        .make-sub-colors(@accent-colors, "accent");
        &-text{
            color: @default-color !important;
            .make-sub-colors(@lighten-colors, "text-lighten");
            .make-sub-colors(@darken-colors, "text-darken");
            .make-sub-colors(@accent-colors, "text-accent");
        }
    }

    .light-blue{
        @default-color: #03a9f4;
        @lighten-colors: #29b6f6, #4fc3f7, #81d4fa, #b3e5fc, #e1f5fe;
        @darken-colors: #039be5, #0288d1, #0277bd, #01579b;
        @accent-colors: #80d8ff, #40c4ff,#00b0ff,#0091ea;
        background-color: @default-color !important;
        .make-sub-colors(@lighten-colors, "lighten");
        .make-sub-colors(@darken-colors, "darken");
        .make-sub-colors(@accent-colors, "accent");
        &-text{
            color: @default-color !important;
            .make-sub-colors(@lighten-colors, "text-lighten");
            .make-sub-colors(@darken-colors, "text-darken");
            .make-sub-colors(@accent-colors, "text-accent");
        }
    }

    .cyan{
        @default-color: #00bcd4;
        @lighten-colors: #26c6da, #4dd0e1, #80deea, #b2ebf2, #e0f7fa;
        @darken-colors: #00acc1, #0097a7, #00838f, #006064;
        @accent-colors: #84ffff, #18ffff,#00e5ff,#00b8d4;
        background-color: @default-color !important;
        .make-sub-colors(@lighten-colors, "lighten");
        .make-sub-colors(@darken-colors, "darken");
        .make-sub-colors(@accent-colors, "accent");
        &-text{
            color: @default-color !important;
            .make-sub-colors(@lighten-colors, "text-lighten");
            .make-sub-colors(@darken-colors, "text-darken");
            .make-sub-colors(@accent-colors, "text-accent");
        }
    }

    .teal{
        @default-color: #009688;
        @lighten-colors: #26a69a, #4db6ac, #80cbc4, #b2dfdb, #e0f2f1;
        @darken-colors: #00897b, #00796b, #00695c, #004d40;
        @accent-colors: #a7ffeb, #64ffda,#1de9b6,#00bfa5;
        background-color: @default-color !important;
        .make-sub-colors(@lighten-colors, "lighten");
        .make-sub-colors(@darken-colors, "darken");
        .make-sub-colors(@accent-colors, "accent");
        &-text{
            color: @default-color !important;
            .make-sub-colors(@lighten-colors, "text-lighten");
            .make-sub-colors(@darken-colors, "text-darken");
            .make-sub-colors(@accent-colors, "text-accent");
        }
    }

    .green{
        @default-color: #4CAF50;
        @lighten-colors: #66BB6A, #81C784, #A5D6A7, #C8E6C9, #E8F5E9;
        @darken-colors: #43A047, #388E3C, #2E7D32, #1B5E20;
        @accent-colors: #B9F6CA, #69F0AE,#00E676,#00C853;
        background-color: @default-color !important;
        .make-sub-colors(@lighten-colors, "lighten");
        .make-sub-colors(@darken-colors, "darken");
        .make-sub-colors(@accent-colors, "accent");
        &-text{
            color: @default-color !important;
            .make-sub-colors(@lighten-colors, "text-lighten");
            .make-sub-colors(@darken-colors, "text-darken");
            .make-sub-colors(@accent-colors, "text-accent");
        }
    }

    .light-green{
        @default-color: #8bc34a;
        @lighten-colors: #9ccc65, #aed581, #c5e1a5, #dcedc8, #f1f8e9;
        @darken-colors: #7cb342, #689f38, #558b2f, #33691e;
        @accent-colors: #ccff90, #b2ff59,#76ff03,#64dd17;
        background-color: @default-color !important;
        .make-sub-colors(@lighten-colors, "lighten");
        .make-sub-colors(@darken-colors, "darken");
        .make-sub-colors(@accent-colors, "accent");
        &-text{
            color: @default-color !important;
            .make-sub-colors(@lighten-colors, "text-lighten");
            .make-sub-colors(@darken-colors, "text-darken");
            .make-sub-colors(@accent-colors, "text-accent");
        }
    }

    .lime{
        @default-color: #cddc39;
        @lighten-colors: #d4e157, #dce775, #e6ee9c, #f0f4c3, #f9fbe7;
        @darken-colors: #c0ca33, #afb42b, #9e9d24, #827717;
        @accent-colors: #f4ff81, #eeff41,#c6ff00,#aeea00;
        background-color: @default-color !important;
        .make-sub-colors(@lighten-colors, "lighten");
        .make-sub-colors(@darken-colors, "darken");
        .make-sub-colors(@accent-colors, "accent");
        &-text{
            color: @default-color !important;
            .make-sub-colors(@lighten-colors, "text-lighten");
            .make-sub-colors(@darken-colors, "text-darken");
            .make-sub-colors(@accent-colors, "text-accent");
        }
    }

    .yellow{
        @default-color: #ffeb3b;
        @lighten-colors: #ffee58, #fff176, #fff59d, #fff9c4, #fffde7;
        @darken-colors: #fdd835, #fbc02d, #f9a825, #f57f17;
        @accent-colors: #ffff8d, #ffff8d,#ffea00,#ffd600;
        background-color: @default-color !important;
        .make-sub-colors(@lighten-colors, "lighten");
        .make-sub-colors(@darken-colors, "darken");
        .make-sub-colors(@accent-colors, "accent");
        &-text{
            color: @default-color !important;
            .make-sub-colors(@lighten-colors, "text-lighten");
            .make-sub-colors(@darken-colors, "text-darken");
            .make-sub-colors(@accent-colors, "text-accent");
            &.text-accent-2{
                color: #ffff00 !important;
            }
        }
    }

    .amber{
        @default-color: #ffc107;
        @lighten-colors: #ffca28, #ffd54f, #ffe082, #ffecb3, #fff8e1;
        @darken-colors: #ffb300, #ffa000, #ff8f00, #ff6f00;
        @accent-colors: #ffe57f, #ffd740,#ffc400,#ffab00;
        background-color: @default-color !important;
        .make-sub-colors(@lighten-colors, "lighten");
        .make-sub-colors(@darken-colors, "darken");
        .make-sub-colors(@accent-colors, "accent");
        &-text{
            color: @default-color !important;
            .make-sub-colors(@lighten-colors, "text-lighten");
            .make-sub-colors(@darken-colors, "text-darken");
            .make-sub-colors(@accent-colors, "text-accent");
        }
    }

    .orange{
        @default-color: #ff9800;
        @lighten-colors: #ffa726, #ffb74d, #ffcc80, #ffe0b2, #fff3e0;
        @darken-colors: #fb8c00, #f57c00, #ef6c00, #e65100;
        @accent-colors: #ffd180, #ffab40,#ff9100,#ff6d00;
        background-color: @default-color !important;
        .make-sub-colors(@lighten-colors, "lighten");
        .make-sub-colors(@darken-colors, "darken");
        .make-sub-colors(@accent-colors, "accent");
        &-text{
            color: @default-color !important;
            .make-sub-colors(@lighten-colors, "text-lighten");
            .make-sub-colors(@darken-colors, "text-darken");
            .make-sub-colors(@accent-colors, "text-accent");
        }
    }

    .deep-orange{
        @default-color: #ff5722;
        @lighten-colors: #ff7043, #ff8a65, #ffab91, #ffccbc, #fbe9e7;
        @darken-colors: #f4511e, #e64a19, #d84315, #bf360c;
        @accent-colors: #ff9e80, #ff6e40,#ff3d00,#dd2c00;
        background-color: @default-color !important;
        .make-sub-colors(@lighten-colors, "lighten");
        .make-sub-colors(@darken-colors, "darken");
        .make-sub-colors(@accent-colors, "accent");
        &-text{
            color: @default-color !important;
            .make-sub-colors(@lighten-colors, "text-lighten");
            .make-sub-colors(@darken-colors, "text-darken");
            .make-sub-colors(@accent-colors, "text-accent");
        }
    }

    .brown{
        @default-color: #795548;
        @lighten-colors: #8d6e63, #a1887f, #bcaaa4, #d7ccc8, #efebe9;
        @darken-colors: #6d4c41, #5d4037, #4e342e, #3e2723;
        background-color: @default-color !important;
        .make-sub-colors(@lighten-colors, "lighten");
        .make-sub-colors(@darken-colors, "darken");
        &-text{
            color: @default-color !important;
            .make-sub-colors(@lighten-colors, "text-lighten");
            .make-sub-colors(@darken-colors, "text-darken");
        }
    }

    .blue-grey{
        @default-color: #607d8b;
        @lighten-colors: #78909c, #90a4ae, #b0bec5, #cfd8dc, #eceff1;
        @darken-colors: #546e7a, #455a64, #37474f, #263238;
        background-color: @default-color !important;
        .make-sub-colors(@lighten-colors, "lighten");
        .make-sub-colors(@darken-colors, "darken");
        &-text{
            color: @default-color !important;
            .make-sub-colors(@lighten-colors, "text-lighten");
            .make-sub-colors(@darken-colors, "text-darken");
        }
    }

    .grey{
        @default-color: #9e9e9e;
        @lighten-colors: #bdbdbd, #e0e0e0, #eeeeee, #f5f5f5, #fafafa;
        @darken-colors: #757575, #616161, #424242, #212121;
        background-color: @default-color !important;
        .make-sub-colors(@lighten-colors, "lighten");
        .make-sub-colors(@darken-colors, "darken");
        &-text{
            color: @default-color !important;
            .make-sub-colors(@lighten-colors, "text-lighten");
            .make-sub-colors(@darken-colors, "text-darken");
        }
    }

    .shades{
        @black-color: #000000;
        @white-color: #FFFFFF;
        @transparent-color: transparent;
        &.black{
            background-color: @black-color !important;
        }
        &.white{
            background-color: @white-color !important;
        }
        &.transparent{
            background-color: @transparent-color !important;
        }
        &-text{
            &.text-black {
                color: @black-color !important;
            }
            &.text-white{
                color: @white-color !important;
            }
            &.text-transparent{
                color: @transparent-color !important;
            }
        }
    }

    .black {
        @color: #000000;
        background-color: @color !important;
        &-text {
            color: @color !important;
        }
    }
    .white {
        @color: #FFFFFF;
        background-color: @color !important;
        &-text {
            color: @color !important;
        }
    }
    .transparent {
        @color: transparent;
        background-color: @color !important;
        &-text {
            color: @color !important;
        }
    }