An example of creating your own icon based on the standard.

ic_arrow_back_24dp.xml

<vector xmlns:android="http://schemas.android.com/apk/res/android"
    android:width="24dp"
    android:height="24dp"
    android:viewportWidth="24.0"
    android:viewportHeight="24.0">

    <!--standard icon-->
    <path
        android:fillAlpha="0.2"
        android:fillColor="#FF000000"
        android:pathData="M20,11H7.83l5.59,-5.59L12,4l-8,8 8,8 1.41,-1.41L7.83,13H20v-2z" />

    <!--custom icon-->
    <path
        android:fillColor="#FF000000"
        android:pathData="M12,4 L13.4,5.4 L6.8,12 L13.4,18.6 L12,20 L4,12z M6,11 L20,11 L20,13 L6,13z" />

</vector>