CODE EXAMPLE FOR CSHARP

particles are pink - creating tex and material

void Start()
{
    createParticleSys();
}

void createParticleSys()
{
    //Create GameObject to hold the Particle System
    GameObject psObj = new GameObject("Particle System");
    //Add Particle System to it
    ParticleSystem ps = psObj.AddComponent<ParticleSystem>();

    //Assign material to the particle renderer
    ps.GetComponent<Renderer>().material = createParticleMaterial();
}

Material createParticleMaterial()
{
    //Create Particle Shader
    Shader particleShder = Shader.Find("Particles/Alpha Blended Premultiply");

    //Create new Particle Material
    Material particleMat = new Material(particleShder);

    Texture particleTexture = null;

    //Find the default "Default-Particle" Texture
    foreach (Texture pText in Resources.FindObjectsOfTypeAll<Texture>())
        if (pText.name == "Default-Particle")
            particleTexture = pText;

    //Add the particle "Default-Particle" Texture to the material
    particleMat.mainTexture = particleTexture;

    return particleMat;
}