private void createFlame(){
                flame = new ParticleEmitter("Flame", ParticleMesh.Type.Point, 32);
                flame.setSelectRandomImage(true);
                flame.setStartColor(new ColorRGBA(1f, 0.4f, 0.05f, 1f ));
                flame.setEndColor(new ColorRGBA(.4f, .22f, .12f, 0f));
                flame.setStartSize(1.3f);
                flame.setEndSize(2f);
                flame.setShape(new EmitterSphereShape(Vector3f.ZERO, 1f));
                flame.setParticlesPerSec(0);
                flame.setGravity(0, -5, 0);
                flame.setLowLife(.4f);
                flame.setHighLife(.5f);
                flame.getParticleInfluencer().setInitialVelocity(new Vector3f(0, 7, 0));
                flame.getParticleInfluencer().setVelocityVariation(1f);
                flame.setImagesX(2);
                flame.setImagesY(2);

                AssetManager assetManager = getApplication().getAssetManager();
                Material mat = new Material(assetManager, "Common/MatDefs/Misc/Particle.j3md");
                mat.setTexture("Texture", assetManager.loadTexture("Effects/Explosion/flame.png"));
                mat.setBoolean("PointSprite", true);
                flame.setMaterial(mat);
                explosionEffect.attachChild(flame);
            }
This test's particle effects (using an explosion)
jme3-screenshot-tests/src/test/java/org/jmonkeyengine/screenshottests/effects/TestExplosionEffect.java