// set some options
GMarkerClusterOptions options = new GMarkerClusterOptions();
options.setMinimumClusterSize(3);
List<GMarkerClusterStyle> styles = new ArrayList<GMarkerClusterStyle>();
GMarkerClusterStyle style1 = new GMarkerClusterStyle();
style1.setUrl(image1).setHeight(26).setWidth(30);
GMarkerClusterStyle style2 = new GMarkerClusterStyle();
style2.setUrl(image2).setHeight(35).setWidth(40);
GMarkerClusterStyle style3 = new GMarkerClusterStyle();
style3.setUrl(image3).setHeight(44).setWidth(50);
styles.add(style1);
styles.add(style2);
styles.add(style3);
options.setStyles(styles);