Run this code and press any key.

import javafx.application.Application;
import javafx.event.EventHandler;
import javafx.scene.Group;
import javafx.scene.PerspectiveCamera;
import javafx.scene.PointLight;
import javafx.scene.Scene;
import javafx.scene.input.KeyEvent;
import javafx.scene.paint.Color;
import javafx.scene.paint.PhongMaterial;
import javafx.scene.shape.Sphere;
import javafx.stage.Stage;

public class PhongMaterialToString extends Application {
    
    PhongMaterial pm;
    
    @Override
    public void start(Stage stage) throws Exception {
        pm = new PhongMaterial();
        pm.setDiffuseColor(Color.LIGHTGRAY);
        pm.setSpecularColor(Color.rgb(30, 30, 30));
        Sphere sphere = new Sphere();
        sphere.setMaterial(pm);
        sphere.setScaleX(100);
        sphere.setScaleY(100);
        sphere.setScaleZ(100);
        PointLight pl = new PointLight(Color.RED);
        pl.setTranslateZ(-1000);
        
        Group root = new Group(sphere, pl);
        root.setTranslateX(250);
        root.setTranslateY(250);
        Scene scene = new Scene(root, 500, 500, true);
        scene.setCamera(new PerspectiveCamera());
        scene.setOnKeyPressed(new EventHandler<KeyEvent>() {

            @Override
            public void handle(KeyEvent t) {
                System.out.println(pm.toString());
            }
        });
        stage.setScene(scene);
        stage.show();
    }

    public static void main(String[] args) {
        launch(args);
    }
}