Laser-drilled
Laser drilling reaches or removes dark internal inclusions in a gem. The drilled channel may remain or be filled afterwards to improve appearance. Laser drilling must be disclosed.
On this page
Naming rule
- Naming rule
- Laser-drilled [material name]
- Market differences and mutual recognition
- No code in the CIBJO Gemstone Book 2022 covers laser drilling, which is essentially a diamond practice. Here too FTC §23.14 routes diamonds to the §23.24 test, and GB/T 16552 puts laser drilling on the treatment side.
Gem treatments compares how every treatment on this site is named and what each must disclose.
Where the treatment acts (schematic)
Laser drilling to reach or remove dark internal inclusions; the channel may remain or be subsequently filled to improve appearance.
- Diamond (cross-section)
- Dark inclusion
- Laser beam (schematic symbol)
- Laser drill channel
- Strong acid (acid boiling)
- Inclusion bleached lighter or dissolved
If you reuse this animation, please credit LumaLark Wiki and link to this pageLicense: CC BY 4.0
Scene-by-scene transcript (4 scenes, with sources)
The caption of each scene in the animation above (the first scene lists its three panel captions), with sources.
Scene 1Laser drilling (laser-drilled diamond as the example)
Before: Laser drilling targets dark inclusions inside a diamond.
During: A focused, pulsed laser burns a narrow channel from the surface to the dark inclusion, and the diamond is then deep-boiled in strong acid.
After: The inclusion is bleached lighter or removed altogether, while the channel stays in the diamond for good, usually a straight, tube-like channel running from the surface to the inclusion.
Treated zone: drill channel and inclusion
Sources
- A History of Diamond Treatments, by Thomas W. Overton and James E. Shigley (Gems & Gemology, Spring 2008, Vol. 44, No. 1, pp. 32–55)
- A New Lasering Technique for Diamond, by Shane F. McClure et al. (Gems & Gemology, Summer 2000, Vol. 36, No. 2, pp. 138–146; full-issue PDF)
- Fracture-Filled Diamonds Detected in Mounted Jewelry, by Sumit Vardawat, Ashok Prajapati and Roxane Bhot Jain (Lab Notes, Gems & Gemology, Winter 2025, Vol. 61, No. 4, p. 394; Lab Notes section PDF pp. 392–399)
Scene 2Process conditions
A focused, pulsed laser burns a narrow channel from the surface to the dark inclusion, and the diamond is then deep-boiled in strong acid. Diamond absorbs almost none of the 1064 nm laser light used, so the target spot is first marked with dark ink: the ink absorbs enough heat to turn the underlying diamond into graphite, which is then converted to carbon dioxide gas, and once started the process sustains itself. The acid is a strong one such as sulfuric or hydrochloric.
Scene 3How it works
The channel is there primarily to let the bleaching acid into the diamond, and it also lets out the gases produced when the laser vaporizes the diamond; it is mainly the acid that bleaches or dissolves the inclusion. When an inclusion does not clear completely, the lasering may have been inadequate, or the material may respond differently to the acid: sulfides are easily attacked by acids, graphite is not.
Scene 4After treatment and how it is detected
The inclusion is bleached lighter or removed altogether, while the channel stays in the diamond for good, usually a straight, tube-like channel running from the surface to the inclusion. The diamond burned out of the hole cannot be replaced. For a diamond that is only laser drilled, with nothing filled in afterwards, the clarity grade may or may not be affected; the trade generally finds a 'white' appearance more acceptable than a dark spot that returns no light. The hole can also be filled with high-RI glass to make it less apparent, but that is a further treatment: glass filling is not permanent, and because the filler is unstable GIA does not issue grading reports for fracture-filled diamonds.
Conventional laser drilling is straightforward to detect: provided the whole stone can be examined, the drill hole is easily visible with a gemological microscope. GIA has disclosed laser drilling on its diamond grading reports since first documenting the process in 1970, lists 'laser drill hole' first in the key to symbols, and laser channels are recorded as clarity features. Another lasering method, the KM treatment, uses the laser to extend existing feathers around an inclusion, or create new ones, out to the surface instead of leaving a conventional drill hole; it takes careful microscopic examination under various lighting to recognize, and GIA reports note 'Internal laser drilling is present'.
Sources
- A New Lasering Technique for Diamond, by Shane F. McClure et al. (Gems & Gemology, Summer 2000, Vol. 36, No. 2, pp. 138–146; full-issue PDF)
- A History of Diamond Treatments, by Thomas W. Overton and James E. Shigley (Gems & Gemology, Spring 2008, Vol. 44, No. 1, pp. 32–55)
- Fracture-Filled Diamonds Detected in Mounted Jewelry, by Sumit Vardawat, Ashok Prajapati and Roxane Bhot Jain (Lab Notes, Gems & Gemology, Winter 2025, Vol. 61, No. 4, p. 394; Lab Notes section PDF pp. 392–399)
How the naming authorities record it
This table scrolls sideways on narrow screens.
| Column | Value |
|---|---|
| Description | Laser drilling to reach or remove dark internal inclusions; the channel may remain or be subsequently filled to improve appearance. |
| GIA code | L |
| LMHC number / note | No matching CIBJO trade code (Annex B, clause 7.2's code list does not include laser drilling); LMHC has no matching Information Sheet |
| GB/T category | Treatment (GB/T 16552-2017 §5.4.1 Table 1: laser drilling is classified as treatment, remark cell empty; representation method at §5.4.2.2). |
| CIBJO disclosure requirement | CIBJO Gemstone Book 2022 §5.82 is the Treated gemstones general clause (CIBJO has no standalone laser-drilling definition clause or trade code). CIBJO Gemstone Book 2022 §4.2.5.2 sets out the disclosure method. |
| FTC regulatory citation | §23.14: treatments to diamonds are to be disclosed in the manner prescribed in §23.24. §23.24 general rule: disclosure is required if the treatment is not permanent (a), creates special care requirements (b), or has a significant effect on value (c). §23.24 names no individual treatment, so Part 23 does not say which of (a)–(c) laser drilling meets. |
| RAL / German declaration | No public source text: RAL 560 A5 is a paid document not on file on this site, so no RAL/DGemG wording is shown (unchecked) |
| JJA/AGL (Japan) treatment disclosure | JJA/AGL 2025 §1-2-1 lists laser drilling (item ⑩) among the treatments applied to natural stones; §2-1-1: the treatment is to be stated to the extent it can be known. |
| AGTA code | L — a laser (with chemicals) used to reach and alter inclusions, usually in diamonds (GIM 17th ed., p.V). Every treatment applied must be listed, e.g. diamond "LF" for lasering and filling (p.IV). Consumer disclosure must be in plain language; codes alone are not sufficient (p.III). |
| Gem-A position | The Gem-A By-Laws have no laser-drilling-specific rule. §7.e.iii: before purchase the buyer should be told if the stone is known to have been treated and, where relevant, how that may affect its durability; §7.b: CIBJO guidelines and definitions are taken as best practice. |
| Naming rule | Laser-drilled [material name] |
| Disclosure requirement | Must be disclosed. Used mainly on diamond; after treatment the remaining channel may be filled with glass or resin, and if it is filled, the filling must be disclosed as well; the laser channel is irreversible. |
| Typical materials treated | Diamond |
| Market differences and mutual recognition | No code in the CIBJO Gemstone Book 2022 covers laser drilling, which is essentially a diamond practice. Here too FTC §23.14 routes diamonds to the §23.24 test, and GB/T 16552 puts laser drilling on the treatment side. |
Materials on which it is recorded
Materials listed for this method in GB/T 16552-2017 Table B.1
This table scrolls sideways on narrow screens.
| Material (row) | Method | Effect | Category |
|---|---|---|---|
| Diamond | Laser drilling | Improves clarity | Treatment |
JJA/AGL table entries relating to this treatment
Other treatments
Sources
This table scrolls sideways on narrow screens.
| Authority | Document | Version | Clause | Source |
|---|---|---|---|---|
| GB/T | GB/T 16552-2017 | 2017 | §5.4.1 | Source |
| GB/T | GB/T 16552-2017 | 2017 | Table 1 | Source |
| GB/T | GB/T 16552-2017 | 2017 | §5.4.2.2 | Source |
| CIBJO | CIBJO Gemstone Book | 2022 | §5.82 | Source |
| CIBJO | CIBJO Gemstone Book | 2022 | §4.2.5.2 | Source |
| FTC | 16 C.F.R. Part 23 | §23.14 | Source | |
| FTC | 16 C.F.R. Part 23 | §23.24 | Source | |
| JJA/AGL | JJA/AGL definitions and nomenclature for gems (Japanese-language document, no official English title) | issued January 2015, revised November 2025 | §1-2-1 | Source |
| JJA/AGL | JJA/AGL definitions and nomenclature for gems (Japanese-language document, no official English title) | issued January 2015, revised November 2025 | §2-1-1 | Source |
| AGTA | AGTA Gemstone Information Manual | 17th edition, August 2026 | p.V (L) | Source |
| AGTA | AGTA Gemstone Information Manual | 17th edition, August 2026 | p.IV | Source |
| AGTA | AGTA Gemstone Information Manual | 17th edition, August 2026 | p.III | Source |
| Gem-A | Gem-A By-Laws §7 Code of Practice (Gem Code) | 2009 revision | §7.e.iii | Source |
| Gem-A | Gem-A By-Laws §7 Code of Practice (Gem Code) | 2009 revision | §7.b | Source |
What the eye can and cannot tell
A laser reaches a dark inclusion inside a diamond through a drilled channel, and the channel may be left open or filled with glass afterwards to improve appearance. Where it was filled, that is two separate facts to declare rather than one. Diamond is the only material listed for this process.
What to ask for on the report
Where the drill channels were filled, AGTA's rule that every treatment be listed applies; its own example is a diamond coded LF, lasered and filled. A listing that stops at laser-drilled while the channels carry glass has declared half of the work.
Before you buy: what to check
Work through these in order before paying. None of them replaces a laboratory report; they decide whether you need one.
- A laser reaches a dark inclusion inside a diamond through a drilled channel, and the channel may be left open or filled with glass afterwards to improve appearance. Where it was filled, that is two separate facts to declare rather than one. Diamond is the only material listed for this process.
- Where the drill channels were filled, AGTA's rule that every treatment be listed applies; its own example is a diamond coded LF, lasered and filled. A listing that stops at laser-drilled while the channels carry glass has declared half of the work.
- Must be disclosed. Used mainly on diamond; after treatment the remaining channel may be filled with glass or resin, and if it is filled, the filling must be disclosed as well; the laser channel is irreversible.
Questions about this treatment?
Disclosure practice for this treatment differs between authorities and markets, and a report does not always say what was done.